Mass Air Flow Sensor question for V40 T4

Hi to all,
I'm wondering if someone can help me.
I have a 2001 V40 2.0 T4. It drives quite well, most of the time, but the engine warning light is on constantly and fault codes show the engine is running lean.
After recent checks by a Volvo specialist in Tyneside, they said they were sure the problems were caused by the mass air flow sensor. They qouted £250 to fit a Hella MAF, but I was also toying with buying a VDO sensor from an online company.
I want to fit a Volvo fit version rather than an unknown cheap one like those found on ebay and I haven't found an original fit part from a breakers so far. The VDO is cheaper than the Hella, but I'd be grateful if anyone has opinion about fitting either.
Many thanks.

How about you introduce yourself first, before steaming in with a Question! http://www.vpcuk.org/forums/forumdis...oduce-Yourself

:buttkick:

I dont have much experience with volvo's but i have c30 d5 and have used this breakers in preston for a mother board for my xenon lights. Was very pleased with the service i got. The phone number 01772 709221. Hope i could help as some people on here think that you have to give them your life story to ask a question about your car!

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Originally Posted by Davoc30d5

I dont have much experience with volvo's but i have c30 d5 and have used this breakers in preston for a mother board for my xenon lights. Was very pleased with the service i got. The phone number 01772 709221. Hope i could help as some people on here think that you have to give them your life story to ask a question about your car!

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Thanks very much Davoc30d5. I appreciate the information and number. I'll give them a ring this week to see if I can get an original part.

Your welcome!

Maf sensors are incredibly easy to fit, even i did my own. Get genuine, much better.
Onto the problem, my friend had a very similar sounding issue when he had a t4 many years ago and it turned out to be the Lambda sensor. Specifically the first sensor and not the one that fits onto the exhaust near the cat.

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Originally Posted by LiamT4

Maf sensors are incredibly easy to fit, even i did my own. Get genuine, much better.
Onto the problem, my friend had a very similar sounding issue when he had a t4 many years ago and it turned out to be the Lambda sensor. Specifically the first sensor and not the one that fits onto the exhaust near the cat.

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That's very interesting, I'm now wondering whether that Lambda might be playing a part and possibly what's affecting it running lean if O2 isn't measured right? I might start with the Maf, but I'll definitely keep in mind what you said and move on to checking the Lambda if a Maf change doesn't work. Thanks for your help.

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Originally Posted by V4T

but the engine warning light is on constantly and fault codes show the engine is running lean.

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..Volvo 'specialists' are good at diagnosing MAF sensors as it's a Cheap and easy fix. Fitting a brand new one will obviously make the car run better over an older or slightly dirty MAF.

I'm not saying it isn't the MAF and I agree with Liam that you should fit genuine BOSCH.
Most of the time EML 'on' with 'system running lean' fault codes are caused by an air leak. Not always easy to find as a leak as small as a pin hole can cause issues. Before shelling out £200 on a new MAF, I'd consider all other avenues first before hand. I'd also clean the MAF before I'd replace it!

Just remember, any leak post MAF will cause the issue you have.

Things to check (not exhaustive list):

MAF to TURBO pipe and post MAF intake hose
All vacuum tubing (lots on a turbo car)
intake manifold gasket
any one way valves in the larger vacuum tubing (they can leak)
Intercooler - they crack.
any rubber 'O' rings for the Boost pressure sensor, MAP sensor etc.

Hi LeeT5,
Thanks for your help. I cleaned the sensor about a month ago with Liqui Moly air flow sensor cleaner and cleared the codes with a simple OBD reader and software. It seemed like it was ok at first, but light came back on soon afterwards and the same codes returned. I understand your comments about air leaks. After the MAF clean, I hunted for air leaks and sprayed with carb cleaner post Maf looking for them, but couldn't find anything. That's when I decided to take it to the Volvo specialist. They looked for leaks as well and said they had smoke tested it, but found nothing.
I'm interested in what you mentioned in your list of things to check. I didn't check things like one way valves or even think about rubber 'O' rings in boost pressure sensor and MAP sensor, so that's very useful. I'm not sure whether the garage I took it to checked those things or not?
I agree that fitting a new MAF might be excessive without being sure that something else isn't playing a part. I was hoping to try a used MAF, give that a clean and try it to see if it made the difference.
There is something else which might just play a part...I don't know. Every now and then, the DSA light comes on. It might stay on for 15 minutes, then go out again. Very occasionally, it has caused erratic power delivery, but most of the time nothing happens whether on or off.
I appreciate your comments. I'll keep them in my mind while trying to get to the bottom of this. Thanks again

Not sure how many one way valves are on a V40 T4, but if they leak, they won't show up on a smoke leak test because the leak will be internal! They will however, if leaking, throw a MAF code and will also casue erractic idle while the ECM adjusts the fuelling to compensate and settle things down.
They are easily tested by removing and blowing on them. They only bypass one way.
Best thing is to just replace them cos they can also be a bit hit and miss.

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Originally Posted by V4T

Hi to all,
I'm wondering if someone can help me.
I have a 2001 V40 2.0 T4. It drives quite well, most of the time, but the engine warning light is on constantly and fault codes show the engine is running lean.
After recent checks by a Volvo specialist in Tyneside, they said they were sure the problems were caused by the mass air flow sensor. They qouted £250 to fit a Hella MAF, but I was also toying with buying a VDO sensor from an online company.
I want to fit a Volvo fit version rather than an unknown cheap one like those found on ebay and I haven't found an original fit part from a breakers so far. The VDO is cheaper than the Hella, but I'd be grateful if anyone has opinion about fitting either.
Many thanks.

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For any sensors for the T4 do NOT go aftermarket.

This model is so sensitive to sensors just bite the bullet and buy the correct one from Volvo.

If for any reason you don`t and you are unlucky and get problems which you almost certainly will, then you have to go and buy Volvo anyway so just buy in the first place.

Of course if you know of a good used Volvo sensor then OK.

Reading Error Codes is a must do.......

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Originally Posted by 960kg

For any sensors for the T4 do NOT go aftermarket.

This model is so sensitive to sensors just bite the bullet and buy the correct one from Volvo.

If for any reason you don`t and you are unlucky and get problems which you almost certainly will, then you have to go and buy Volvo anyway so just buy in the first place.

Of course if you know of a good used Volvo sensor then OK.

Reading Error Codes is a must do.......

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Hi 960kg. Many thanks for your advice.

I've been busy with work lately, which is why I can't always respond to posts as quickly as I'd want, but I've been thinking a lot about the inputs from people here. When I get a chance shortly, I'm going to check around the engine some more, especially items such as those mentioned previously by LeeT5 and LiamT4. It's useful to know that some things like the one way valves sound as though they're straightforward to remove and test.

960kg, you said don't go aftermarket with Volvo and reading error codes is a must do. The garage I took the car to seemed certain that it was a MAF problem after their VIDA code reading and leak testing.

I've found a seller of a used original Volvo Siemens MAF from a 2001 car for about £40. I thought I'd give it a go along with other checks. He claims it’s in “good working order”. I hope it is. The MAF has 'Volvo Siemens Germany' moulded into it and the part codes on it seem to be correct for the T4's chassis number. I haven’t been able to find a Bosch version.

I'm aware that the MAF might not be the problem. I'm re-reading some things LeeT5 said about EML 'on' with 'system running lean' fault codes is often caused by an air leak and smoke testing not showing up faulty items such as one way valves. They're could easily be an air leak somewhere.

Having said that, I'm thinking that if I throw in the MAF and see whether there's an improvement, then at least I'll have found something out. If it makes matter worse, then I'll try to send it back. I'll then have to go through the list of potential problem/leak areas.

Hi

I thought I'd give an update...

The second hand Volvo Siemens MAF arrived. I cleaned it with liqui moly and fitted it. I cleared the fault codes using the Torque Pro android app and a cheap bluetooth OBDII reader that I have. The engine light went out and I'm pleased to find (so far) that it hasn't come back on. I've done a few hundred miles in the car since fitting and there are still no fault codes.

The DSA light hasn't come on either and the fan run on, that was happening regularly even when the engine was cool, has stopped. Tickover is smooth and the car pulls cleanly.

I'm very pleased, but it's interesting how many things were badly affected by the old faulty MAF.

Thanks to everyone who posted for their help.

Glad you sorted it.

Im in the same boat with this problem. Erratic revs and maf code. Take the maf off it runs perfect.. put back on its back to being weird...

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Originally Posted by Matt_kouki

Im in the same boat with this problem. Erratic revs and maf code. Take the maf off it runs perfect.. put back on its back to being weird...

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Remove and clean the MAF first. Refit, clear codes and drive....

Do the erratic revs return?
Do the MAF fault codes come back?

What codes are you getting?

They do indeed. No volvo breakers here in belfast, and i see everybody saying the ebay items are no good