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Old 21st December 2014, 11:24   #1
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Default VW Vento: Contaminated MAF sensor

Does anyone know the location of the MAF (Mass Air Flow) sensor on the Vento Petrol version? I need to check the sensor for contamination. I've been getting the EPC light intermittently and the fault code shows P2637. A quick look up on the net shows that the most common cause for this fault is a contaminated MAF sensor. I also read in a different post (on team-BHP) that the K&N filter causes contamination of the MAF sensor due to the oil. Incidentally, I am using a K&N filter which I recently cleaned and re-oiled. The VW service center chaps could not do much as the fault is intermittent. Any help would be most appreciated.

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Old 21st December 2014, 21:42   #2
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Default re: VW Vento: Contaminated MAF sensor

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Originally Posted by jethari View Post
. Incidentally, I am using a K&N filter which I recently cleaned and re-oiled. The VW service center chaps could not do much as the fault is intermittent. Any help would be most appreciated.

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Hari
There is your answer, the oil from the flter has contaminated the sensor earlier than normal. Try removing sensor and cleaning it by lightly spraying or soaking it in methyl alcohol
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Old 21st December 2014, 22:04   #3
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Default re: VW Vento: Contaminated MAF sensor

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There is your answer, the oil from the flter has contaminated the sensor earlier than normal. Try removing sensor and cleaning it by lightly spraying or soaking it in methyl alcohol
Thanks. Trying to figure out how to get at the sensor. The air filter housing is mounted right on top of the air intake manifold. I can see the throttle butterfly once I remove the filter element, but that's about it. Might have to remove the air filter housing to access the MAF sensor.
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Old 22nd December 2014, 08:08   #4
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Originally Posted by jethari View Post
Thanks. Trying to figure out how to get at the sensor. The air filter housing is mounted right on top of the air intake manifold. I can see the throttle butterfly once I remove the filter element, but that's about it. Might have to remove the air filter housing to access the MAF sensor.

Its very likely that the oil of your K&N filter caused this. You re not the first one, neither will you be the last one to whom this happens. The filter really only needs a very little oil.

Cant you find the location of the sensor? Check for the wires, usually somewhere after the air filter. The sensor itslef, typically is a tiny holder which has shows an open, very thin wire, facing toward the incoming air. Ideally, you should clean it with special MAF cleaning solution. If you cant find something like an electro cleaner. Make sure its one that doesnt leave any residue.

Lots of videos on Youtube:



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Old 22nd December 2014, 11:42   #5
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Default re: VW Vento: Contaminated MAF sensor

what if we do not get those MAF cleaner sprays, what can we use instead? The guy on the video was very adamant that we should not use anything else. Someone mentioned Methyl Alcohol in the above post. Would that be ok?
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Old 22nd December 2014, 12:11   #6
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Default re: VW Vento: Contaminated MAF sensor

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what if we do not get those MAF cleaner sprays, what can we use instead?
Rubbing alcohol or iso-propyl alcohol. A bottle is available at medical stores/chemists.

Put the sensor in a plastic bag/zip-lock bag with the solution and shake it to get rid of the dirt stuck on the sensor element. Take the assembly out, let it dry and replace it back.

Moderator ajmat had posted a link on this - DIY : Cleaning your MAF Sensor for Rs 120
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Old 22nd December 2014, 22:22   #7
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Default Re: VW Vento: Contaminated MAF sensor

MAF is a critical thing. I can surely say that after the faulty MAF of my 3L Safari took toll on engine and finished it. I had to rebuild the engine. Problem was everytime I took the vehicle above 2k RPM the check engine light indicating faulty MAF would appear. I simply ignored that and kept driving with check engine light on, meanwhile the MAF kept on screwing the Air-fuel mixture. This continued for 50K kms and the engine started consuming oil, then, within next 10K kms I had to rebuilt the engine. The car is currently with mechanic and the TASC is claiming their sum of money 18K for a bloody MAF sensor? The same costs 6K for 2.2vtt. I had to order it online from UK (ebay), lets see what happens.

The point is get it rectified as soon as possible.
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Old 22nd December 2014, 23:04   #8
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Default Re: VW Vento: Contaminated MAF sensor

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MAF is a critical thing. I can surely say that after the faulty MAF of my 3L Safari took toll on engine and finished it. I had to rebuild the engine. Problem was everytime I took the vehicle above 2k RPM the check engine light indicating faulty MAF would appear. I simply ignored that and kept driving with check engine light on, meanwhile the MAF kept on screwing the Air-fuel mixture. This continued for 50K kms and the engine started consuming oil, then, within next 10K kms I had to rebuilt the engine. The car is currently with mechanic and the TASC is claiming their sum of money 18K for a bloody MAF sensor? The same costs 6K for 2.2vtt. I had to order it online from UK (ebay), lets see what happens.

The point is get it rectified as soon as possible.

So lets get this right, you drove 50.000 kilometres with a CEL? Not sure how you would correlate a CEL to faulty MAF? Or why a faulty MAF would lead to oil consumption? Don't understand why the engine had to rebuilt either?

But if the morale of the story is it might be useful to get faults seen to, I would agree. But nothing in your story suggest that it was a faulty MAF that leads to an engine rebuild. Even so, driving 60.000 kilometres knowing that something is wrong must be some sort of record.

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Old 23rd December 2014, 21:15   #9
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Default Re: VW Vento: Contaminated MAF sensor

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Even so, driving 60.000 kilometres knowing that something is wrong must be some sort of record.

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Well, almost every private minibus I've travelled in (Mahindra and Tata CNG buses) run with their CEL light on, and a lot of taxis as well. Haven't checked on the DTC buses though.
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Old 23rd December 2014, 21:19   #10
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Default Re: VW Vento: Contaminated MAF sensor

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Well, almost every private minibus I've travelled in (Mahindra and Tata CNG buses) run with their CEL light on, and a lot of taxis as well. Haven't checked on the DTC buses though.

True, and to be honest it is very rare for a CEL fault to have a real big impact on the engine as such. CEL is related to the emissions of the engine. Could be as simple as a fuel cap not properly closed, or a MAF not working properly. By and large these CEL faults are more damaging to the environment then to your engine so to speak.

So why do you think your faulty MAF sensor was the reason for a complete engine overhaul?

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Old 23rd December 2014, 21:33   #11
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Default Re: VW Vento: Contaminated MAF sensor

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Originally Posted by Jeroen View Post
True, and to be honest it is very rare for a CEL fault to have a real big impact on the engine as such. CEL is related to the emissions of the engine. Could be as simple as a fuel cap not properly closed, or a MAF not working properly. By and large these CEL faults are more damaging to the environment then to your engine so to speak.

So why do you think your faulty MAF sensor was the reason for a complete engine overhaul?

Jeroen
I don't have any idea about why the engine in question failed. I was only remarking how CV drivers who depend on their vehicles for their livelihood drive with the CEL on. If it was really serious, they would have got it fixed. In fact, the manual of my Zen calls it the "emission control system malfunction" light.

Regarding the engine in question, isn't the 3L Safari a diesel engine? Why will bad fuelling kill it? The knocking caused by a lean mixture in a gasoline engine can't happen in a diesel. Isn't a diesel supposed to be "knocky"? The cetane number for diesel signifies faster combustion, which is opposite of octane number. So a bad MAF will only cause it to belch smoke.
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Old 29th January 2015, 11:20   #12
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Default Re: VW Vento: Contaminated MAF sensor

Some updates here: Still have not figured out where the MAF sensor is. However, was advised by a friend to use a good "Carb Cleaner" into the air intake. I got myself a can of STP Carb Cleaner, removed the air filter to access the throttle body and butterfly. Started the engine and let it warm up till the cooling fan cut in. Then with the throttle raised to about 2000-2500 rpm, sprayed the Carb cleaner in short bursts into the throttle body (into the air intake). The engine tends to stutter and splutter when the cleaner is sprayed (that is why spray in short bursts). Sprayed 8 - 10 bursts and kept the engine running for some time. Put everything back and have been driving for more than three weeks now - no sign of the EPC or CEL light so far .
The engine is also perceptibly smoother than before. So far so good, I'll keep you updated.

Hari
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Old 29th January 2015, 18:46   #13
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Default Re: VW Vento: Contaminated MAF sensor

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Originally Posted by jethari View Post
Some updates here: Still have not figured out where the MAF sensor is. .... I got myself a can of STP Carb Cleaner, removed the air filter to access the throttle body and butterfly. Started the engine and let it warm up till the cooling fan cut in. Then with the throttle raised to about 2000-2500 rpm, sprayed the Carb cleaner in short bursts into the throttle body (into the air intake). The engine tends to stutter and splutter when the cleaner is sprayed....

Hari
You SHOULD NOT spray any cleaners into the intake manifold while the engine is running. Especially with EFI cars.

THe MAF sensor is usually on the tubing from the air filter just before the throttle boddy. If you look through the pipe, it will look like a grill.
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Old 29th January 2015, 18:53   #14
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Default Re: VW Vento: Contaminated MAF sensor

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Originally Posted by jethari View Post
Some updates here: Still have not figured out where the MAF sensor is. However, was advised by a friend to use a good "Carb Cleaner" into the air intake. I got myself a can of STP Carb Cleaner, removed the air filter to access the throttle body and butterfly. Started the engine and let it warm up till the cooling fan cut in. Then with the throttle raised to about 2000-2500 rpm, sprayed the Carb cleaner in short bursts into the throttle body (into the air intake). The engine tends to stutter and splutter when the cleaner is sprayed (that is why spray in short bursts). Sprayed 8 - 10 bursts and kept the engine running for some time. Put everything back and have been driving for more than three weeks now - no sign of the EPC or CEL light so far .
The engine is also perceptibly smoother than before. So far so good, I'll keep you updated.

Hari
Quote:
Originally Posted by HimuraKenshin View Post
You SHOULD NOT spray any cleaners into the intake manifold while the engine is running. Especially with EFI cars.

THe MAF sensor is usually on the tubing from the air filter just before the throttle boddy. If you look through the pipe, it will look like a grill.
My dear friend Himurakenshin is 100% correct!
You should also not be spraying any cleaner or any solution while the engine is running!

This should be used when the engine is not running. And you should only start the engine once everything is dry.
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Old 29th January 2015, 19:03   #15
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Default Re: VW Vento: Contaminated MAF sensor

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Originally Posted by HimuraKenshin View Post
You SHOULD NOT spray any cleaners into the intake manifold while the engine is running. Especially with EFI cars.

THe MAF sensor is usually on the tubing from the air filter just before the throttle boddy. If you look through the pipe, it will look like a grill.
There is no tubing between the filter housing and the throttle. The filter housing fits directly on top of the throttle - anyone with a Vento petrol model, open the housing and take a look for yourself.

I dont quite agree with SHOULD NOT spray any cleaners into the intake manifold. The STP carb cleaner is a water based cleaner that breaks up the carbon deposit (soot) in the tubings and helps vapourize it.

Hari
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