MAF Sensor - clean or replace?

[prprandall51]

Hello experts, can you please help?

My car (211 E320 Cdi 2005) has gone into Limp Home mode (limited power, max 3000rpm, no kickdown, max speed approx 50mph).

From reading the many posts on this forum about these symptoms it appears the MAF sensor is most likely at fault (though it will need diagnostics to confirm - so this is not a definite diagnosis).

What I want to know is: is it worth taking it off and blowing it out with a compressed air cannister (as used to clean computer insides) to see if it works again, or is it most likely to need replacing (if it is indeed the MAF sensor).

I don't mind half an hour fiddling with it if it can genuinely be fixed with a clean out but I don't want it to fail again in a few thousand miles, either, possibly leaving me with a very long, slow journey home.

On the other hand, if a clean-out fixes it, I would rather that than book it into the garage and all that that involves.

Thanks
Philip

 

[smoothcoupe]

Try crc air mass senor cleaner. You can get it on ebay for a tenner. Remove sensor and spray carefully on the hotwire ( gently). I did this on my 2000 jaguar xjr. It absolutely worked wonders.

 

[jonathanc]

I know with earlier cars if you unplug the MAF the car will use some default values and will run, all be it not as well as with a good MAF in place, this might be worth ago to prove it is the MAF before you spend money. Also, it is worth trying to clean it, if it is causing the car to go into limp home then I don't see how cleaning could make it any worse! I guess the obvious advice is to get the codes read to positively identify the MAF

 

[prprandall51]

Thanks for the replies. It looks like cleaning the MAF isn't too onerous a task and could provide a permanent fix - which is essentially what I hope for. I will give it a go. If the problem isn'tr fixed I will take it in to get the codes read.

Philip

 

[ray_hennig]

Try cleaning it ...

It looks like cleaning the MAF isn't too onerous a task and could provide a permanent fix - which is essentially what I hope for. I will give it a go.

We cleaned the MAF on my son's VW Gti Mk IV a couple of years ago and it's been fine ever since.

We removed it and then sprayed the hot wire with electrical contact cleaner. We then put cleaner on to those cotton wool buds that you use to clean a baby's ears. The hot wire was gently wiped with the wet buds and then replaced into the car.

All misfire/idle issues were solved and it's been fine ever since.

RayH

PS: And the baby's ears are spotless!

 

[prprandall51]

Since posting this thread, I have been reading up on MAF sensors in other forums (fora?). It seems that many car owners treat the cleaning of the MAF sensor as a regular servicing requirement that manufacturers simply omit from the service schedule.

I shall certainly clean mine and see if it solves the Limp home mode problem. I will post back how I get on.

 

[The _Don]

Hello experts, can you please help?

My car (211 E320 Cdi 2005) has gone into Limp Home mode (limited power, max 3000rpm, no kickdown, max speed approx 50mph).

From reading the many posts on this forum about these symptoms it appears the MAF sensor is most likely at fault (though it will need diagnostics to confirm - so this is not a definite diagnosis).

What I want to know is: is it worth taking it off and blowing it out with a compressed air cannister (as used to clean computer insides) to see if it works again, or is it most likely to need replacing (if it is indeed the MAF sensor).

I don't mind half an hour fiddling with it if it can genuinely be fixed with a clean out but I don't want it to fail again in a few thousand miles, either, possibly leaving me with a very long, slow journey home.

On the other hand, if a clean-out fixes it, I would rather that than book it into the garage and all that that involves.

Thanks
Philip

Sell it and buy a c63

 

[prprandall51]

I cleaned the MAF sensor today. The wire had black soot on it so I cleaned it up.

Initial impressions were good - car idles and runs more smoothly, kickdown is available and the engine revs to the redline. In addition, the fuel consumption, which had dropped to 25mpg on the journey which ended in limp home mode (possibly, though, simply because of being in that mode), was straight back up to 37mpg (my typical consumption).

The only problem is the car is now running cool. The gauge is visibly shy of the half way mark (where it has always remained spot on up till now) and the car only reached normal temperature when I was in slow moving traffic - and it may have even got a bit hot and gone over the normal mark.

Could this still be the MAF? I intend taking it to the dealers at this point to see what the diagnostics say but I would welcome any comments on the problem.

Thanks for any input.

Philip

 

[BlackC55]

Cleaning the MAF lasts 5 mins. just buy a new one. They are a serviceable item.

The cool running won't be anything to do with the maf. A diagnostic check wont be able to tell you why it is running cool (unless the fan is running at 100%). 9/10 it needs a new thermostat.

 

[x332race]

Cleaning the MAF lasts 5 mins. just buy a new one. They are a serviceable item.

QUOTE]

I replaced maf when I thought it was suspect...cost me about £50 and 5 mins to fit.

 

[Nasco12]

£50? Sounds like one of those Far-Eastern imports that's only supposed to last 5 mins.

Did it?

 

[prprandall51]

Cleaning the MAF lasts 5 mins. just buy a new one. They are a serviceable item....

MAF Sensor = £226.50 plus VAT! Eeek. Time for proper diagnostics rather than just replacing the sensor to see if it fixes the problem, I think....

 

[Dieselman]

£50? Sounds like one of those Far-Eastern imports that's only supposed to last 5 mins.

It also sounds like the genuine Pierburg sensor from a dealer, ECP or other supplier.

 

[ray_hennig]

Well!

Cleaning the MAF lasts 5 mins.

Er, or 18 months in the case of my son's Gti.

RayH

 

[timskemp]

MAF Sensor = £226.50 plus VAT! Eeek. Time for proper diagnostics rather than just replacing the sensor to see if it fixes the problem, I think....

If cleaning it has brought it back to life be happy. When it needs cleaning again clean it again, until it no longer works.

I think mine came from the local bosch parts dealer, and was about 140+vat.

Being a 211 it'll need a thermostat, "they all do that sir".

 

[prprandall51]

If cleaning it has brought it back to life be happy. When it needs cleaning again clean it again, until it no longer works.

I think mine came from the local bosch parts dealer, and was about 140+vat.

Being a 211 it'll need a thermostat, "they all do that sir".

Hi Timskemp, can you please explain why it'll need a new thermostat - do you mean the coolant thermostat or the thermostat in the sensor itself (I assume the latter as there is - presumably - no connection between the coolin system and the MAF sensor)?

Thanks
Philip

 

[corned]

It seems an odd combination - MAF issues and then a cool running issue.

Is your 320 the I6 or V6 - I can't remember. If it's the I6, then the MAF and thermostat are on opposite sides of the engine, so it is unlikely that you disturbed the sensor wiring on the thermo when looking at the MAF. Otherwise I would have said that this could be a possibility?

I think Tim was referring to the inherent appetite 211s appear to have for coolant thermostats. This usually shows itself by the temp gauge reading way too low for normal circumstances. What you describe in post #8 is typical (coolant) thermostat trouble! Unless the wiring got disturbed of course...

 

[timskemp]

Hi Timskemp, can you please explain why it'll need a new thermostat - do you mean the coolant thermostat or the thermostat in the sensor itself (I assume the latter as there is - presumably - no connection between the coolin system and the MAF sensor)?

Thanks
Philip

The coolant stat - they do seem to need replacing...

 

[prprandall51]

It seems an odd combination - MAF issues and then a cool running issue.

Is your 320 the I6 or V6 - I can't remember. If it's the I6, then the MAF and thermostat are on opposite sides of the engine, so it is unlikely that you disturbed the sensor wiring on the thermo when looking at the MAF. Otherwise I would have said that this could be a possibility?

I think Tim was referring to the inherent appetite 211s appear to have for coolant thermostats. This usually shows itself by the temp gauge reading way too low for normal circumstances. What you describe in post #8 is typical (coolant) thermostat trouble! Unless the wiring got disturbed of course...

The coincidence of MAF and then immediately afterwards a thermostat problem -seems too much, especially as the car warms up quickly and then is only running slightly cold - but then gets hot in traffic: not the typical behaviour of a thermostat stuck open (or closed).

My car is an I6 but I don't know where the temperature sender unit for the radiator is, they are usually screwed into the radiator housing and I might conceivably have disturbed the wiring to that. I certainly had to push and pull a few parts around to get the MAF out.

I am tending towards the theory that I have managed to part fix the MAF. My thinking is that if the MAF is still mis-reading the air flow into the engine then the car will run lean and this could cause cool running, as Dieselman made reference to. I cleaned the wire sensor up and perhaps that brought the sensor back into the range where the engine doesn't suspect it of lieing and thus falling into Limp Home mode.

I am hoping a new MAF will sort it out. Shame the clean-up didn't fix the problem; £270 is a lot for a simple sensor.

 

[Kentish]

I'd really appreciate some advice here. I have a CLK350 on a '57 plate with just 40K on the clock.

The car is out of warrany and I had it serviced recently in a local garage, where they used to service some of the cars - Audi and VW - that I owned previously. I've have good service and I've been happy with the worj they've done previously.

Anyway, to come back the the point. The showed an error fault within hours of me picking up from the service and the diagnostics show that the MAF sensor as being the source of the problem. The garage is telling me that MAF sensor needs to be replaced, but I also been told that maybe the MAF sensor only needs to be taken out and 'cleaned' and that it doesn't need to be replaced? It's a bit of a dilemma, not least because hte OEM parts are coming in at circa £220 alone, though replacing it s looks simple enough? (I've seen the show on youtube, of course?)

I'd be really grateful of any advice or suggestions you maybe able to give me about resolving this problem?

Many thanks.

Steve