The Mass Air Flow sensor (MAF) is a crucial component of an electronic fuel injection system in a car, installed between the air filter and the engine’s intake manifold. It measures the amount of air entering the engine or the air flow. The primary role of the MAF sensor is to detect the air mass flow rate getting into the engine, which helps the engine control unit determine the fuel level supplied to the engine. It works effectively with an oxygen sensor for accurate measurement.
The MAF sensor is integral to modern vehicle performance, accurately measuring incoming air, enabling precise control of the air-fuel mixture, which is crucial for efficient combustion. It is used in almost all modern petrol and diesel engines to calculate the optimum amount of fuel to be added. There are two main types of MAF sensors:
Mass Air Flow Sensor: This sensor is an integral part of your vehicle’s engine management system. It measures the air mass flowing into the engine intake, which is important for calculating the amount of fuel to add to achieve the proper air-fuel ratio (AFR). The ideal AFR is 14.7:1, but AFR can vary.
Mass Air Flow Sensor: This sensor is a device in the throttle body that helps the engine computer determine the proper air-fuel mixture by measuring the mass of the air. The MAF sensor detects the airflow through the engine’s intake and converts variable airflow into an electrical value. One of its main functions is to measure the amount of air entering the combustion chamber.
Most MAF sensors work with an oxygen sensor to calculate the injected fuel. The MAF sensor plays a fundamental role in increasing engine efficiency by measuring the amount of air entering the internal combustion engine.
📹 EVERY ENGINE SENSOR EXPLAINED – MAF, MAP, IAT, TPS, 02, NOx, EGT – How it works, location, OBD2 code
00:00 Intro 00:57 Crankshaft position sensor 02:54 Camshaft position sensor 03:58 Throttle position sensor TPS 05:44 Mass air …
What is the main function of a MAF sensor?
Air mass information is crucial for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. In automotive applications, air density varies with ambient temperature, altitude, and forced induction, making mass flow sensors more appropriate than volumetric flow sensors. There are two common types of mass airflow sensors used in automotive engines: the vane meter and the hot wire. Both designs output a 0. 0-5.
0 volt or pulse-width modulation (PWM) signal proportional to the air mass flow rate, and both have an intake air temperature (IAT) sensor incorporated into their housings for most post-on-board diagnostics (OBDII) vehicles. Vehicles prior to 1996 could have MAF without an IAT.
What is the average life of a MAF sensor?
The mass air flow sensor is a crucial component in the engine, measuring the air entering the engine and allowing the computer to calculate the proper air and fuel mixture. It typically lasts between 80, 000 miles to 150, 000 miles. Proper maintenance and cleaning can prolong the life of the mass air flow sensor.
One common symptom is hard starting, which can be caused by a faulty air flow sensor. To diagnose this, remove the sensor from the inlet tube or air filter box and inspect the filament for any dirt or contamination. If the filament is dirty, use an approved air flow sensor cleaner and reinstall the air flow. If the vehicle starts up normally, the fault is due to a dirty mass air flow.
When the sensor starts acting up, the vehicle may hesitate when in motion or jerk when trying to give it gas. A completely dead sensor may prevent the automatic transmission from properly engaging, causing a delay in driving during cold start-up.
How do I know if my MAF sensor needs to be cleaned?
The mass airflow sensor (MAF) is a crucial component in an automobile, monitoring the amount of air flowing into the engine from the outside. It helps the engine control module (ECM) make adjustments to the air and fuel mixture needed for combustion. If the MAF is dirty or going bad, it can cause issues such as hard starting or turning over, engine hesitation, hiccups, and fuel mixture problems.
One sign of MAF issues is difficulty starting or turning over, which could be due to a dead MAF sensor. If the sensor is dead or dirty, it won’t send the proper readings to the ECM, causing starting problems. Additionally, a stalling engine is another sign of MAF issues. If the ECM sends incorrect air readings, the engine may stall, leading to fuel-starved or flooded engines. Willoughby Hills Auto Repair can clean or replace the MAF if it’s dirty or going bad.
What happens when the MAF sensor goes bad?
A malfunctioning mass air flow (MAF) sensor can result in a range of drivability issues, including engine stalling, jerking, or hesitation during acceleration. Such problems have the potential to cause accidents and injuries, particularly when driving on highways or city streets.
How to check if the MAF sensor is working?
To test a MAF sensor, use a multimeter to measure voltage and resistance. Connect the red probe to the signal wire of the MAF sensor connector, usually the middle one. A faulty MAF sensor can cause poor engine performance, increased fuel consumption, and emission issues. To test a MAF sensor, use a multimeter, a screwdriver, and compressed air. Before working on the sensor, disconnect the negative terminal of the battery to prevent electrical damage or short circuits. Loosen the nut holding the terminal cable and secure it away from the battery post. This step is crucial to ensure proper functioning of the MAF sensor and prevent potential issues.
What happens if you don’t have a mass air flow sensor?
A faulty mass airflow sensor can cause engine issues, such as rough running or misfiring, due to an imbalanced air-to-fuel ratio. This imbalance prevents the powertrain control module from determining the necessary fuel for the engine, leading to uneven combustion. Sometimes, the engine won’t start or turn over, indicating an imbalanced air-to-fuel ratio. To fix this issue, the mass airflow sensor needs to be replaced. Black smoke from the exhaust also indicates an imbalanced air mass within the engine intake, potentially posing a dangerous level.
What happens if you don’t have a MAF sensor?
The mass air flow sensor is crucial for the powertrain control module (PCM) to accurately calculate the engine’s fuel needs, preventing it from running too lean or too rich, leading to rough engine running and misfiring. If the car struggles for power and stalls frequently, it may be getting too much air and too little fuel, causing the combustion process to fail. Dirty buildup on the wires in the mass air flow sensor can cause this.
A local automotive maintenance professional can repair the wires. Black exhaust smoke, a sign of a problem, could indicate a damaged mass air flow sensor, causing the engine control model to calculate improper fuel injection, resulting in black smoke.
What are MAF functions?
MAF is a leucine zipper TF of the AP superfamily 9 that regulates various developmental processes, including the development of follicular T helper cells and M2 macrophages. Its expression pattern in the B lineage has not been defined, but its functions include promoting differentiation, stromal adhesion ability, and cytokine gene regulation. MAF can be directly oncogenic when overexpressed in different cell types, but its role in humans as a direct oncogene with tumor-initiating capability has been shown only in myeloma (MM), an incurable malignancy of bone marrow plasma cells (PCs).
Myeloma initiating events (MIEs) include chromosomal hyperdiploidy or translocations that bring MMSET, CCND1, and MAF to the vicinity of an IgH enhancer. These events occur during Ig class-switch recombination in germinal center B (GCB) cells. Only PC-derived myeloma and not GCB or post-GCB cell lymphomas are associated with MAF, suggesting that PCs provide the permissive cellular context for the malignant potential of MAF to be realized.
The well-studied MAF-associated transcriptional signatures highlight the MAF-dependent deregulation of oncogenes, such as cell cycle regulator CCND2 and ITGB7. However, how oncogenic MAF molds chromatin and the regulatory genome that determines the distinct transcriptional oncogenic program associated with t(14;16) in MM remains unknown.
Can a car run without a mass air flow sensor?
The user is experiencing a problem with their car’s ignition, which may go into fail-safe or stop accelerating. They have ordered a new one but are still 3 hours away from home. The problem could be related to a bad connection at the PCM or MAF, wiring fault, or the PCM itself. If the MAF doesn’t resolve the issue, complete diagnostics would need to be run. The user is uncertain if it will be possible to drive the car home and if the problem persists after replacing the new one.
What will happen if I disconnect the MAF sensor?
It is inadvisable to disconnect the MAF sensor while the vehicle is in operation, as this may result in the engine stalling due to the computer losing the necessary information. To diagnose a potential issue with the MAF sensor, it is recommended to disconnect the sensor, start the vehicle, and observe for any changes.
Why do I need a MAF sensor?
The mass air flow sensor is of vital importance for the optimal functioning of the vehicle’s internal combustion engine, as it is responsible for regulating the air-to-fuel ratio, thereby ensuring the engine’s optimal performance. It is of the utmost importance to conduct regular checks and maintenance in order to ensure optimal functionality.
📹 Mass Air Flow Sensor – Hot Wire – Explained
How does a mass air flow sensor work? What is a MAF sensor? This video explains how a hot wire type mass air flow sensor …
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I was a motor mechanic in the 1960’s, early 70’s then moved into the aviation industry so I missed the whole shift from simple mechanical linkage operation to electronic sensors, ECU’s and actuators. I’m retired now and have just started working on my own cars again, upgraded my tool kit, bought an OBDII scanner, and am re-training myself to understand the tangle of pipes, tubes, sensors and wires that are under the bonnet of modern cars. This article was really helpful and clarified a few things I was unsure about.
This is pure gold, thanks for taking the trouble to make and upload this. Just one thing I would like to add, regarding fault-finding: very frequently the sensor isn’t actually at fault. Instead, it’s a connector somewhere between the sensor and the engine management computer. Replacing the sensor will often clear the fault because a new sensor comes with a new connector. Still, I always suggest, before spending time and money replacing a sensor believed at fault, separate connectors, spray with contact cleaner, re-assemble, re-test. I have been repairing electronics systems for 4 decades and have more experience of failed (or intermittent, even worse) connectors than I would wish on anyone!
I grew up not caring about cars or having anyone to teach me about them, but as I recently have become a car owner (of an older model at that) and ran into some issues with my O2 sensor, I’ve become super curious about how cars work. Stuff like this is invaluable because I want to understand what my mechanic is talking about when he tells me what’s wrong and what needs to be fixed, and maybe one day I’ll be able to do some repairs myself. Thanks so much!
Well done! This demonstrates how complicated engines are. I was driving once on the highway and suddenly the speed dropped from 110 KM/h to 50 KM/h. The vehicle wouldn’t accept speeds of over 60 KM/h. From idle, when I try to accelerate, the engine would shutdown. So I took it to an automotive shop and they used the latest diagnosis tools and they couldn’t find the problem. They said the transmission (automatic) needs to be replaced, and they said that they see a misfiring on one of the cylinders. They charged me $200 for their diagnosis without finding out the actual problem. They failed to check the very basic components, which I then did myself, and I am not a mechanic, and found the engine air filter ripped. I went and replaced the air filter with a FRAM filter that cost me $11 at Walmart and everything was fixed. Obviously, the ripped air filter allowed large air mass to flow in and the ECU couldn’t accommodate the high signal reading of the MAF sensor, hence it was shutting down the engine. This is one useful example of this great article of what sensors do and how important they are to running the engine. PS. that vehicle I had was a Nissan Pathfinder 2000 SE 4X4 model.
This guy is absolutely outstanding when it comes to thoroughly explaining the workings of an engine in a simplified way. I never worked on an engine until 6 months ago. With a workshop manual, decent mechanics tool kit and his help, I have pulled off updates to my Toyota Hilux LN167 5L 3.0L diesel which have not only saved me a fortune. But given me the knowledge of how my vehicle works and the sense of accomplishment for achieving something I never though I would. Hats off to you mate!
I’m leading a small team of people that are supposed to audit repairs done in the workshops of a big OEM. Most of my team never worked in the automotive. This article (and many others from you) are a huge help to enable my team to understnad multiple principles of the tech used in today’s vehicles. But I also have to admit that, after many years in this industry, these articles are also a big help for me to understand better or remember some of the stuff I should know. Many, many thanks for doing all this work 🙂
I have no idea why you don’t have more subscribers. Your articles are masterpieces. The research, the delivery, and the graphics and animations are all brilliant. I don’t know where you could find this collection of information anywhere else with such good instruction. Thank you very much for your work.
Thank you for creating this informative article about car engine sensors. It’s great to see a comprehensive breakdown of each sensor, including its function, location, and potential issues if it goes bad. Additionally, providing the corresponding OBD2 error codes for each sensor is extremely helpful for those who are troubleshooting engine problems. This article is a valuable resource for car enthusiasts and mechanics alike. Keep up the excellent work!
This article untangled a mess of my electrical problems on a 2016 Cadillac ATS. I have six different codes showing up. I now better understand what these sensors do and where they are located. With knowledge, I can now do things I could not do before. What an incredible article. Thank you a million times. Maybe I will finally get this car out of my life. Hurray!
I’ve slowly taught myself how to work on cars over the years ever since I was little. Most of my learning has been stuff messing up on my dad’s project cars and now mine. Even though I’ve been learning for years, articles like this are still INVALUABLE to learn exactly why I’m replacing the things I am. It also helps out to better diagnose problems
This article was fantastic! Thank you so much for taking the time to make this interesting, informative, and easy to watch! Perhaps you can make a future article about the other (non-engine) sensors used for airbag deployment, rain sensing wipers, automatic climate control, automatic headlights, and so forth. Thanks again!
Galvanized Greatness brought up a great point! All of your articles, except maybe engine specific, should be in auto tech schools as a part of their curriculum! I sure wish I had these articles available to me when I was in auto tech school. I’m very thankful for them today though to keep expanding my knowledge of the engine. Thank you D4A! You are the best!
This article is absolute poetry! Articulate, thorough and understandable. It deserves as many “thumbs-up” as the number of views it has received. I am a first-time visitor to your articles and you have gained an instantaneous, well deserved subscription. Thank you very much for an outstanding presentation.
D4A thank you making this article, I’m a motorcycle mechanic and have to deal with most of these sensors, you helped me understand how exactly they interact with the motor and made it to where I could explain it to the old boys. I just got my little brother into your articles too keep up the good work, peace be with you.
I started a fulltime automotive job back in the 70’s and seen the advancement of electronic engine control over the years until I retired (ASE Master Tech) in 2017. When I started, Chrysler is starting to add electronic ignition on their vehicles. Then GM and Ford fallowed. Then they started making computer controlled carburetors. Oxygen sensor was called Lambda then. European and Asian were using CIS (Continuous Injection System). The big three were using TBIs ( Throttle Body Injection). Then non-sequential (gang bang) port fuel injection followed by port sequential fuel injection. The ECM (Electronic Control module) was changed to PCM (Powertrain Control Module) when the module is controlling the engine and transmission. Now they have Direct Fuel Injection but it wasn’t perfect because of the carbon build up in the valve seat causing driveability problems. They had to go back and add a port fuel injection to wash the carbon build up. I’ve learned that even you memorized all the function of the sensors and know how to use the scanner, there is a time that a problem exist but no DTC. Also start your troubleshooting first by visual inspection. Sometimes you can fix the problem without even connecting the scanner. Don’t make a mistake by thinking its an electronic problem right away. Nice presentation.
Great article! Super concise and interesting! Another tip about MAF sensors for anyone that might see this is that when you unplug a MAF on pretty much any vehicle the ecu will change to a default fuel map. So if you’ve got a P0101 or other maf code/the engines running like garbage, unplug the MAF and if the engine starts running like normal you know where your problem is 👌
Another symptom of a bad throttle position sensor is unpredictable up-/down-shifting of the automatic transmission while cruising. The faulty TPS gives the ECU an erroneous signal and the ECU thinks the throttle is open further than it really is, so it tells the trans to downshift. I had this happen on two of my Jeeps. I now carry a spare TPS and the correct Torx driver to change it beside the road. Good article, sir.
Invaluable article for a home mechanic! I have a 2016 Equinox with a 2.4L Ecotech. Problem was it would start run 2-5 seconds and stall in P or N. No check engine light, no code. I changed both valve advance solenoids no help. I replaced high press fuel pump, no help. I disconnected the MAF sensor and car ran with check engine light and now a code. I tried cleaning it with MAF sensor cleaner no help. Spend $70 for new sensor and fixed it. It kicked my ass because there was no check engine light or code. This article is awesome and I saved it to my favorites. Ty for making it.
Amazing work mate. Thank you very much for producing this highly informative article. You have and will continue to help people such as myself who want to learn more about their vehicle and what each component does so in turn we can repair our selves or at least have an understanding of what the mechanic plans to achieve. That being said i feel there are alot of cowboy mechanics that wouldn’t know where or what half these sensors do. Thank you again 🙂
I love when “mechanics” say, I don’t work on that brand, they’re different. I always give them a brief statement. A 3 wire sensor is a 3 wire sensor, regardless of brand. I put voltage, ground and signal. It’s task may vary, but it’s function is simple To figure out and diagnose once you realize the basic functions.
Buddy, I broke my MR2T. This winter I installed an upgraded turbo and a brand new ACT HDSS Clutch. I got a great spring and early summer out of it but I killed it. I’m hoping it’s just the clutch but I may have launched an e153 transmission into retirement. Sorry, had to vent to someone who would understand. I’m feeling very defeated ATM. But I’ll be back.
Brother thanks so much this is probably the best well explaned article about all sensors and posible failures or diagnost it really explaned how they work wat they do on good shape bad shape even location makes the knoledge and the possible solution saving lost of money to the ownership and more easy understanding thank you so much
very useful, i remember when my MAF sensor had a more or less manufacture defect and was causing very rough idling and stalling even tho it was an automatic the reason was if very slight preasure was applied to the plastic housing, it would stop working and cause the engine to die, with all of the vibrations of the engine it was basically pressing that defect spot a bunch and causing a lot of running issues
Oh. My. 😮. You just might have literally saved my life by creating this article and sharing it with the world. I’m not even exaggerating. Somebody hateful recently vandalized my vehicle from the inside out with the intention of disrupting its functioning but in a manner so that the effects are delayed enough to allow a separation of time between their actions and consequences so as to appear as having no part in the vehicle’s malfunctioning (whew, long sentence, sorry). I didn’t have enough of a global understanding of the engine operation to be able to explain the situation to anybody else….but I really think I might be able to now that I watched your article! Omg thank you for this info, presented the way you did!
@ 13:32 Once working on a car (2001 Saturn SL2) I forgot to attach back one sensor on Air Duct, I think it was Intake Air Temperature sensor. On that car the sensor is located kind of close to the bottom of the Air Duct, so I put back the AD and forgot about that sensor. The result was: I started the car, I don’t remember what I was checking and how the engine was running, but then I stopped the car. But the engine was running. I removed the key, to my astonishment the engine was still running. I stopped the engine only by disconnecting the battery. Not sure what kind of process happened there, but from that time I always carry a corresponding wrench in the glove department for the battery in every car. Very good review on engine sensors. Thank you. So is it like every sensor on a car would be an Engine Sensor, or there are some not related to the engine? Thank you again.
This is really helpful! This shows how simple all of these electronics that control the vehicle really are! (Most seem to run on variable resistance or have a 3 wire setup). My question is, are some of these sensors universal? Can you use an oxygen sensor or coolant temp sensor in any vehicle or is it brand or even vehicle specific?
Well, I thought this was a really excellent article, but then I had a good look at my 1958 Austin Healey and I can’t find any of these devices on it, so I’m not sure what you’re talking about! On a slightly more serious note, we did some tuning work back in the 1980s on engines fitted with K-Jetronic injection (a largely mechanical system), and we ended up renaming the vane-type Air Flow Meter as the Air Flow Strangulator. On an even more serious note, this article is superb and contains a very noticeable lack of bullshit. I’ve subscribed.
On EEC-IV fords (late 80’s early 90’s) the crank position sensor is part of the distributor. The distributor gear is attached to the crank, then under the rotor is a toothed “bell” that passes between a Hall effect pickup that goes to the EEC. Neat stuff. Rarely see them fail but when they do you need to rebuild the distributor.
Thanks for this mate 👍,It looks simple enough but before perusal this article of yours i wouldn’t have known what was what especially that 2nd hose on the egr,I didn’t even know there was another pipe to go on there,It doesn’t feel like another pipe would even fit on there 😂,you made it very straight forward and correct,Thanks again.
Yet another outstanding article thank you. I know it’s outside the remit of this article, but many so-called Technicians replace parts as soon as they see a fault code, without reading the fault code description and checking the basics first. Examples are a MAF fault code, and it’s a split air intake pipe, or an O2 sensor fault and it’s a loose vacuum hose. Many people out there believe that all we have to do is just plug a computer in, and it’ll tell us what’s wrong. I love to point out that it just tells us where to start looking. I’m babbling. Sorry. I love your articles though!
An excellent article as always! Big fan of the website. My O2 sensor heater on my motorcycle failed (tested in accordance with the service manual) and the OEM part is 185 dollars, I found a ‘compatible’ part on amazon for $60. The question that I have is why so much cheaper? I know it’s non-OEM, but still, $120 cheaper? If it is a crappy product, can it damage a part in my motorcycle? Thank you.
nicely explained. i might mention that egt sensors are invaluable in airplane engines which take off full rich, but once established at altitude the pilot will lean the engine by egt to a temp close to max lean, for fuel conservation. also with leaner air at altitude this is a way to visually confirm economy. regards, k
A great article! But I am stuck with many of the symptoms of a sensor not working being the same symptom e.g. running poorly. So how to identify the particular sensor. Is it my scan tool that will help narrow down the sensor. I don’t want to replace a sensor I think is not working properly only to find the sensor I replaced did not need to be replaced. Any suggestions?
this article is great thanks, I was wondering if you think that one of these oxygen sensors was an issue… I do own a Camry SE 2015 and it is giving me like 50 miles less than when I first got it. I just did its first smog check test and it passed ok. I have no idea about what is causing it, any tips that you can think of it? thanks
The info in the article is very useful & can help every skill level of mechanics 1 issue,this pertains to GM only ECM Engine Control Module engine only TCM Transmission Control Module BCM Body Control Module controls the entire car In the article what he calls the ECU Electronic Control Unit on GM cars is the BCM The ECM Engine only
Great article I am still trying to find out why my car will not start. Maybe you can point me in right direction. Car sat for 6 years. It’s a 1998 Volvo S70 GLT. I cleaned out fuel tank, replace fuel pump and fuel filter. I cleaned injectors. Car cranks has spark and fuel out the injectors. I thinking must be a sensor where the timing is not lining up with the spark and injected fuel. Any thoughts? Thanks
Very informative, thanks and even the ads weren’t too intrusive. (which is high praise, coming from me!) I’m still of the “There’s no place for a computer under a bonnet” school. But, as it’s becoming almost impossible to find a vehicle without an ECU -even at the older end of the used market- I suppose I should at least educate myself as to what all these damned sensors are supposed to be for.
Hello there and thanks for the article. Can you please make a article to specifically explain how the Oil level sensors works especially the ones used in Audi’s as I think they depend on both the oil temperature and the capacitive technology but I cannot understand how it combines the two and how accurate they actually are.
now i just need to locate the ones on my Jeep. Its older and some of them have different names than what they use on newer cars. I know my Jeep needs a MAF sensor but I dont think then it was called a MAF sensor on my year of Jeep lol but…. very good article,every little bit of knowledge helps when youre not use to working on your own vehicle! Car mechanics in my country type area seem to know nothing about older jeeps….lol.
My Triumph 675 had a barometric pressure sensor located away from anything inside the tail unit, sheltered from any airflow, close to the numberplate hanger, for measuring ambient air pressure. Would love to hear an explanation of why they needed that, given it presumably also had a mass airflow sensor somewhere 🤔. Wouldn’t that make the barometric pressure sensor kinda pointless ?
okay, so i agree you mentioned all sensors related to the engine! of course there’s far more sensors in the car you didnt mention such as ( wheel speed sensor, steering angle sensor, crash sensor, weight sensor,vehicle speed sensor, etc….) but those sensors doesnt affect the engine performance at all… but there’s one more hidden sensor that could affect the engine performance in a weird exceptional way on rare car which is the yaw rate sensor.. this sensor is installed on the center of gravity of the car which is under the driver seat, it’s function mainly for stability systems such as ( ESP, TCS, ABS etc…) but it happens to me once that a car work perfectly fine, but struggles at accelerations and while going up the hill, while everything in the engine looks fine and no faults has been detected.. the only fault was the yaw rate sensor in the stabilty system. after research, the yaw rate sensor helps the engine control module to knows if a car is accelerating so it could give a injection boost or ascending a hill or descending a hill using accelerometer to notify the engine control module…. weird huh? cars world is insane
Every vehicle I have is no less then 50 years old but hey, its just a personal preference since I don’t really understand computers nor anything more then basic electronics; interesting article nonetheless and learned something too. The future is coming and gots to be prepared in some ways haha. Quite informative.
It is also worth to mention two temperature sensors for coolant (thermostat), and bimetal temperature sensor for turn on/off the fan. The first one is proportional, the second is binary. This are at the same time actuators (valve and switch), to stabilize coolant and engine temperature without electronic control unit. By old engines there by ignition distributor were also centrifugal rotational speed sensor, and vacuum membrane intake air pressure sensor (indirect engine load measurement), to mechanically shift the ignition point, earlier or later, also without ECU.