How to Test a MAF or MAP Sensor With a Multimeter - Plus an Operations Guide

Here is a video on how a Mass Air Flow and a Manifold Absolute Pressure Sensor work and also how you can test them using a basic multimeter.
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Disclaimer:
Due to factors beyond the control of Ratchetsand Wrenches, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. Ratchetsand Wrenches assumes no liability for any property or personal damage that may arise from doing a repair on your vehicle after watching any of my repair video's. Due to factors beyond the control of Ratchetsand Wrenches, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Again Any injury, damage or loss that may result from improper use of tools, equipment, or the information contained in this video is the sole responsibility of the user and not Ratchetsand Wrenches.

[@NZbluesky]

8 YEARS AGO! You sir, are a shining light to people like myself! An old electro mechanical engineer... 2 million views? Fabulous teaching! Greetings from NZ

[@TheRichardmay1]

By far you are the best channel for learning auto systems. your explanations are simple and clear. thank you so much. also great sense of humour every so often.

[@luisaliceaortiz7791]

Richard May thank you for time and efforts I'm always wanting to learn more .stay blessed

[@darrylkishii9359]

Richard May Q

[@andrewngwenya6837]

This video has actually taught me how to distinguish a MAP from a MAF. Many thanks for the lecture.

[@WmTyndale]

Another beautiful explanation. Especially that the IAT sensor is in the MAF in the newer cars. I like your deep knowledge and precise explanations. RECOMMENDED!

[@politicalfoolsandhorses]

So very well explained. Really good. But please note that that MAP sensor is good. It increases the voltage only during acceleration. So if you are doing constant 20MPH it will be 1/1.5 depending on car make - it will go us as son as you decide to go from 30 to 60 and will stay up untill you reach 60 and release the pedal slightly (vacum if you have a vacum meter - many call it economy metres - goes down and Absolulte Pressure returns to normal) and the fuel mixture changes to lean again. At 60 MPH it changes according to the reading of the MAS Airflow Sensor. Anyway - the industry needs more people like you Well done again.

[@arniet1]

Thanks for that info. Is there anything simple that can cause a map sensor fault that can be easily checked without buying a new map?

[@politicalfoolsandhorses]

I am not sure I understand your question. 1. Anything simple that can cause a map sensor fault is. The map sensor is located in the inlet manifold after the air filter - it can get dirty / contaminated especially if you remove the air filter and use a gause filter or a filter which is not so good at filtering the air. Very easy to remove and clean. Many videos on U tube - only one screw maximum 2. It is vey reliable but its an electronic part and does not really like engine vibraions - and the engine heat. So it depends which car. On my car it has 153 K miles and never chaned. On my wife car it was changed after 163 K miles. 2. fault that can be easily checked without buying a new map? I would say that anyone that wants to test the electrinc sensors of his car himself, apart from the fact that deciding which sensor, if any, is the core of any issue to sart with; he should buy a Code Reader also called a Scan tool since it scans/checks all the sensor. Thanks to mass prodyctin these are ridiculously cheap - 24 Dollars sometimes even less from the shop than from Amazon. Googel - "car cheap code readers" or Go here: www.google.com/search?q=cheap+engine+code+tester&oq=cheap+engine+code+tester+&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTIxMDM5ajBqN6gCALACAA&sourceid=chrome&ie=UTF-8 i@@arniet1

[@richardwallinger1683]

You are definitely the man . at 72 years young I understood everything you were testing .. My VW 2.5 TDI 2001 199,000 miles has gradually lost pulling power .I replaced the old original exhaust with a nice new Stainless de cat system .It was marginally more responsive , but after fitting a pressure gauge to the intercooler housing the measured boost topped out at 11 psi. I was told to expect up to 18psi. The MAF sensor was replaced for testing only and the difference was unbelievable the turbo boost increased as before but then continued to increase easily passing the 1 bar pressure gauge I had plumbed in . now all I need to do is attempt to clean the original MAF sensor and see if it was recoverable . my short journey transport is a 2011 Nissan LEAF . Everyone should have one of those .. they are the future.

[@jamesjohnson5700]

Can car have both map & maf?

[@donaldhollums3278]

I'm a long time, automotive DIYer and am getting into doing light automotive repair and service side work. I'be watched a few of your films along with DIY Auto Tech and Scanner Danner to help me improve my diagnostic skills instead of just being a parts changer. You have another subscriber, Amigo. Keep up the great work!

[@davidboles9166]

Great job man! I have searched many videos on various car repairs .You have covered 3 of the problems I have had. You rock bro!!

[@yannickkay5099]

After years your videos still educational videos you teach me easy tricks to test a sensor without wiring diagram that's amazing bro... Thanks sooooo much

[@StormFlinix]

Been watching your vids for years. You know they're good when I come back and refer to them while on my projects

[@vladimirpetrov9717]

The map sensor is fine, when you crack the throttle slowly, the engine spins up, but the throttle does not open further. That causes more vacuum to form inside the intake, typically the map will read about the same as at idle or lower (since the pressure is usually lower). Otherwise cool video!

[@Puppunanne]

petrol engine , normal ....

[@jamesjohnson5700]

Can car have both map & maf?

[@TheWindrunner88]

@@jamesjohnson5700 yes

[@jamesjohnson5700]

@TheWindrunner88 ok because I can't tell if my 2019 Hyundai Elantra se has one as in maf

[@TheWindrunner88]

@@jamesjohnson5700 I’m not sure about those, might be able to google it tho

[@AmharicMusicLyricsVideo]

you are a good mechanic u explain with the mechanism how it works also the volt resistance testing failure solution amazing

[@dondale68]

I do like your videos. Myself, I find some of them boring but I've been working on cars for over 30yrs, but for a novice these are great! Not too much technical detail for them to lose interest, just enough to keep their attention and teach them how to fix their vehicle!

[@W.Khairi]

Regarding car repair this is one of the best watched so far......its a truly door opener.....Thank u very much

[@osvaldoumana4494]

super clear.... great video.... thanks a lot!!!! i just got my new OBDII scanner and with this video I hope I can fix my kids car.... next...THE WORLD!!!!!!

[@ashishacharjee8018]

U r really good.....I just saw another video by an automotive engineer. Combined with ur video, everything fell easily in place. The engineering info with a knowledgeable technician’s experience.....is the best tutorial.....thanks

[@Johnsmith-zi9pu]

To reduce vacuum you have to apply load or disconnect the vacuum tube. That sensor appears to to be working OK.

[@tomreyn3610]

Yea. He is wrong about the MAP. Bad test. Quick rev response was correct. He interpreted in wrong. MAP was good.

[@politicalfoolsandhorses]

There is one think I need add for the less knowledgeable/experienced. Identify the fixed supply voltage first using Volts setting. No damage can be done while testing any pin for volts. HOWEVER ONCE YOU CHANGE TO OHMS, to identify the ground wire, you MUST make sure that you NEVER touch the Supply Voltage Pins again. Under OHMS , the meter will short the supply voltage to earth, blow a fuse which might not blow fast enough and you could cause damage to the electronics, So be warned. You either do it in full conformance with how this man described it or you could do more harm than good.

[@davidsibble7429]

Very very good video..appreciate the attention to theory as well as active repair. Shows true reinforcement to problem solving 👍🏼🙌🏼😎

[@uguraker8930]

Bravo ; for 1-fluent spoke 2- fully own and controlling science of this subject. 3- loving your jobs 4- your teaching talent(gifted , from God)

[@froglegs4910]

I LOVE YOUR AUTO REPAIR LECTURE ! VERY CLEAR EXPLANATION AND TRUELY PRACTICAL ! THANKS LOT FOR YOUR UPLOAD VIDEO !

[@boybravo689]

Sir tnx for showing us how to test a sensor using a voltmeter most of us newbie mechanic can't afford to buy a high end instrument tnx for all the info sir subcriber from the Philippines

[@lorchri14]

Working on Onan generator, EFI, so so helpful to understand these sensors and how to test. The manuals only give resistance parameters out of box, not operational.

[@jettpatton4618]

Hey bud I really liked the way you translated this,you made it very understandable because you know your shit. Thanks bud for taking time to share.

[@wyattoneable]

I missed the cut off but I really have no questions. You do a great job at explaining the components and circuitry so it's just a matter of getting out there and experimenting for myself. Thanks.

[@Chris-hx3om]

No he didn't. He doesn't understand the difference between a 2-wire and a 3-wire sensor.

[@bluor3713]

@@Chris-hx3om what's the difference between a 2-wire vrs 3-wire?

[@Chris-hx3om]

@@bluor3713 2-wire is a resistor and the ECM is looking at the current flowing, whereas a 3-wire is a voltage divider where the ECM is looking at the voltage between two power rails. The advantage of the 2-wire is cost, but at the expense of repeatability with varying voltage rails. (Automotive is notorious for quite a range of voltages. Less than 10 under high load without the engine running, to over 14v once the battery is fully charged.)

[@slimeroad]

Very practical video for determining baseline characteristics for each of these devices. Thanks very much from the UK.

[@OverturecervejariaBr]

Very good video. This is the right way to diagnose the fuel injection system.

[@billyburns3792]

The reason the voltage didn’t go up when you opened the throttle slowly is because you didn’t lose vacuum until you opened the throttle wider

[@Rabbit.760]

Wow you teach better than anybody I know of. So well, that your accent sounds fluent

[@toomuchtruth]

This is exactly the video I need right now as I try to fix my car. Almost like if you made it just for me, lol! Thanks a ton for this!

[@myRatchets]

lol nice, glad its useful to you. cheers

[@davidessien5465]

Nice video! ❤ However, to check for air leak it's better to use a smoke machine to avoid hazard.

[@wrapcityhqvicmelbourneaust6570]

My map sensor went bad and I thought it was the map sensor I just replaced it for ten bux brand-new. Instead of doing all the checking I'm just saying if you want to learn it this is a great channel I like it a lot

[@milesdavis7644]

the quickest way 2 check any sensor in your car at multiple working time is to start your car while the car is running..using a car computer set it on live data if it is avalible on the computer, it will tell you what ever u need 2 know about any sensor live and direct..

[@christen1075]

Step 1. Locate MAP sensor location on your car. Step 2. Reconnect electrical connector to said sensor which had failen off due to the little hooter that holds it in place being broken. Step 3, employ white zip tie to prevent this from happening again, inadvertently. Step 4. Leave nice comment about well taught lessons on MAP and MAF sensors to RnW big guy. Step 5. gloat to your kids how you're now an ace diagnostician. Step 6 sheepishly thank the Lord and RnW for making you learn something without buying a part willy-nilly.

[@bpdp379]

I’m on step 4 currently

[@bilalcassim4509]

one of the best mechanics on youtube keep up the goodwork , good videos and always spot on . helps me 100% of the time

[@IrfanTahir]

your explanation is very precise and simple as well. Great job and thanks

[@lorchri14]

Forgot to add, thank you for getting to the point and not making me filter out off tangent superfluous crap.

[@amogarage]

Great video, helped me successfully diagnose a faulty Map sensor, thanks a million

[@Purosanluispotosi]

So how u know wen that sensor are bad that numbers stay on place or wen go up

[@gasgas2689]

I love this. I must learn more. I have been fixing cars for 50 years, but always the older non-computerised cars. Now I have spent a thousand $ on incompetent garages using their computer diagnostics and believing the computer instead of using the very few brain cells the Lord God gave them. From now on I will watch and learn from you.

[@devsamEXPOSED]

Your MAP sensor was just fine. It measures PRESSURE, not volume. When you open a throttle slowly you barely increasing any pressure but you are increasing the volume which is why it was properly working the way it should.

[@myRatchets]

you might be correct sir, gona have to bench test that thing. will update results.

[@valentinegutierrez3905]

Dev Sam b

[@michelguevara151]

he obviously thinks they're the same thing. bit of a jonny-know-all-wanker.

[@andrinirainyramanantoanari8162]

@@myRatchets So, in the end what was the problem?

[@sandygrungerson1177]

a graphing tool would show any irregularities in the voltage, which is useful for finding intermittent MAF problems

[@RoadRunnerMeep]

Great video, very detailed. What were you using to test for a vacuum leak from the N75 valve when you determined there was no leaks. What should have happened if there was?

[@Jan_Seidel]

Cheers. Learned a lot new MAF in 2 minutes!

[@btibb23]

Not trying to cut you down just adding to the video when trouble shooting a map sensor you must check all vacuum lines not just the one leading to map sensor and as you can tell in the video the map sensor works but when you snap the throttle it does create a high enough vacuum pressure to actuate it but it has a leak else where In the system think about it logically that's not a independent vacuum source it shares with many other ports ya know

[@brianreed5425]

every educational :) thanks for breaking it down barney style

[@perfectus101]

hand that Monkey a Bahnanah Skippy

[@stephenarling1667]

This is great explanation, and much easier to remember after second viewing.

[@ricardoolguin9607]

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[@33798]

Very good explanation of MAP and MAF

[@forsdykesavusi1432]

Thank you for the knowledge that share especially for new mechanics like me god bless you

[@joey243win]

Awesome really helps remember stuff I'd forgotten thank you!!

[@ex8280]

Dang 2 Million DiY'ers was helped by this video. Congrats.

[@juanorte3526]

Thanks! for this video, easy to understand man. I said hi from Uruapan Michoacán México 👍

[@copkhan007]

I actually learned something new today...thanx my friend.

[@fabiobatalhadesa1586]

Hello... I'm Brazilian, see your vídeo very good... congratulation!!

[@LukeSchiralli]

Great video, very informative and easy to follow thanks!

[@carlosgavino6874]

You are so awesome thank you for this straight to the point instructional thank you

[@michaelking42]

Great, great video, thank you for taking the time and effort to make it.

[@Jpilgrim30]

An oscilloscope is about the only reliable way to test a mass airflow. I've seen MANY MAF sensors that looked fine on a scan tool and a multimeter that had tons of glitches when viewed on a scope. Glitches that were far too quick to even hope to see with a meter.

[@oscarronquillo7794]

well said...

[@JrSpitty]

If you wan't to be certain. But good oscilloscopes kind of cost a fortune in contrast to a cheap reliable multi-meter. They also require a lot more proper care.

[@samlloyd8668]

BUT... a cheap DMM will tell you if the sensor is bad. So, you have a point, but a meter isn't totally useless. BTW, What causes the spikes you mention? Is there active circuitry inside the sensor, or is the hot wire the only component? Just curious if the spikes are due to a compromised connection, in which case it might be easily repairable (solder joint issue?), or is the platinum wire welded, making it irreparable?

[@jasonmcnamara2079]

sometimes analogue meters are better than dmm's for this type of stuff

[@tokgaenz]

thanks you so much , all your video is easy to understand and educational

[@RB-er6gu]

Thanks i learned a lot on testing 👍

[@keithjames1682]

Your videos are awesome

[@patrickstankiewicz1345]

Easiest way for map sensor is to have Key ON engine OFF, this simulates wide open throttle(atmospheric pressure present, no vacuum present with engine off). This should give you your 4.4.5V, or your max pressure reading. Then start car and check at idle and compare to specs. Boosted cars don't apply to that though

[@xdygmnyrdf]

man, that's some good info, thanks.

[@AJTarnas]

awesome work. thanks for the diagrams and the clear instructions.

[@marioquimpan4888]

Thank you sir for your valuable knowledge share to everybody.

[@mayamikokayesa171]

well done will get the ball rolling great show

[@bezaleeluk3696]

Don't back-probe sensor plugs in the described manner as you will in all probability damage the moisture seal created at manufacture and shorten the life of the connector to the sensor.

[@draid9564]

I think I have this issue with MAP sensor connector wires. One of the wires was damaged and I had to splice another one in, so I think the connection is not that good causing readings and codes also making the fuel run lean, thanks for the video very helpful.

[@nealeng.1063]

Thanks for this very informative information. Great details !

[@hollowandfaceless8993]

Thank you bro, this truly helped💯

[@marcoaaguilera2620]

Very good video -Good instructor & very knowable.

[@RNMcustom]

Thanks for your effort in helping us understand how things work.

[@myRatchets]

np, glad you liked it. cheers

[@dennislazarte3061]

Very useful discussion..Many will learn from your videos.keep it up and many thanks to you👍👍👍

[@ansarijaved]

all of your vidios are very easy to understand very helpfull..

[@crank3646]

You forget to say few words about digital MAFs . Great informative video as usual !

[@myRatchets]

I did, it didn't make it past the editing room. good point.

[@spike121964]

Love all your videos. Great work

[@paulsassya]

It's a great demo. Thanks a lot I wish you can guide me w/ my pathfinder 2006 .It's cranking but not starting until I try for like 10 times or more.

[@user-jn7or4ry3p]

Great video, be nice to see how it works on newer model cars. Can't pull on the acceleration the same way. 😅

[@edwardharvey5839]

I understand everything now, Thanks!

[@Takeitlightly6]

Orale, good video homes….i see few annoying requests from newbies to show them which wire is what in the connector and instead of talking to them, i will share this video…. Adios…

[@esperancengaffaousadou9717]

Thank you for the video

[@razaji7557]

very good information teacher 🌺

[@berlisss]

thanks a lot for the video, very informative and in simple words. YET! I beg yourpardon for mentioning it, but! with the paperclips could easilly break the rubber seals securing the connection inside of the plugs (from water or whichever liquids). couldn't you?

[@deathxxx1231]

Precious video! Thanks for that!

[@cincomorales]

After this video i subscribed to your chanel ! You are always patient and humble thank you for your videos!

[@dimualdogalangmabungajr9273]

Tankz for your explenation....tnkz so mutch...

[@freesaxon6835]

Excellent reference video

[@t1too]

subscribed cause you told NOT to use ohm position on a wire carrying voltage.basic but folks dont know .new digital meters are forgiving but needle type analog will be fried most times if you try to do that.Be careful with your vom.finally someone not full of b.s.

[@JohnR9965]

You do great easy to follow vids. Two thumbs up.

[@myRatchets]

ty ty

[@muriuwangai3617]

Awesome. Kindly advise me on what tests to carry out on my g16a sidekick engine include TPS, etc

[@grullon120]

thanks Sr. keep making amazing videos, really appreciate your help

[@jorgegutierrez3373]

Mi car was diagnosed by Autozone code P1195 for MAP Sensor. Noticed Check Engine light turned on and off several days at a time that could lead to electric false contact. Made test with multimeter and hand held vacuum pump. Voltage wouldn't go down from 4.50 volts when applying vacuum. I started jerking to one side the cables of the electric plug connected to the MAP sensor then when vacuum at 20 in-Hg suddenly the voltage would drop all the way between 0.85 and 1.15 volts which is the expected value, as soon as stop applying pressure to the cables the voltage would rise up again to 4.50 volts and so on. Changed the electric plug with a used one from junk yard. Reset the check engine light. I have been driving the car for 2 days now and the check engine has not light up again (so far), also the car stopped trying to turn off itself (rev's would go back and forth from 800 to 150 and then go back to 800). Nonetheless I tried to duplicate the test you made in the video about with CAR on for the voltage to increase from 1.0 volt to 3 or 4 volts without success. The initial value in my case is NOT 1.0 volt instead my value is 4.50 volts, when I open the throttle the voltage does not change. Please give me your comments. Mazda Protégé 1996 engine 1.5.

[@garymartin8185]

great video simple n direct to the point. thanks

[@AraceaeFanatics]

Very helpful videos.

[@nainarkumar]

Thank you Master..

[@observersnt]

Thank you for your clear, simple and methodical approach and for the time and effort you have put into these videos. Please forgive my ignorance, I am, as you will see from this question, still learning: If in the course of probing or back probing to identify wires in any connector, I connect my multi meter with its 9 volt battery to any five volt signal wire, is there not a danger that I may damage or destroy the five volt signal generator(?) or regulator in the ECU?

[@stevejohnson8773]

No. The meter is designed so as not to damage the circuitry it is testing.

[@robertoibarra3542]

Thanks for share information

[@golfnut533]

Great info, thanks for your efforts. 👍

[@deepakchavan7943]

Realy nice explanation. Thanls

[@MUHAMMADHADIM]

good bro.... very helpful videos ......thanks... shukira.... from Pakistan islamabad

[@akliaithamou268]

Hi im akli from algeria you know what !! You are awesome I hope learn more from you ,I really want to know much more about all engine sensors

[@Hacker07Gaming]

Holy shit literally what I was looking for