OM642 Exhaust back pressure sensor.

[DSM10000]

My W211 with the OM642 has been a little out of sorts recently.

I have managed to get the EGR replaced as this was showing Position errors as well as other codes.

Strangely at 160k miles the EGR pipework etc was completely clear of deposits except for a light coating of soot

Now there is a problem with the Exhaust back pressure sensor.

Part number A006153028

MB have this sensor on back irder. Are there any other suppliers that people may recommend?

Many thanks.

 

[unclebuck]

Genuine Mercedes Benz OM642 Engine Exhaust Back Pressure Sensor A0091535028 | eBay

Part Number A0091535028. Fair wear and tear and parts fitting incorrectly are not covered under this warranty.

www.ebay.co.uk

none at merc newcastle

just a thought are they saying the one next to your egr is faulty? if so the one above is correct.

If i put the number you have stated in it gives me this part with autodoc which is down on the throttle body pipe

https://www.autodoc.co.uk/car-parts/oem/a0061531528

which sensor is the issue??

Knowing how bad your egr was I would definately change the back pressure sensor out

 

[DSM10000]

Genuine Mercedes Benz OM642 Engine Exhaust Back Pressure Sensor A0091535028 | eBay

Part Number A0091535028. Fair wear and tear and parts fitting incorrectly are not covered under this warranty.

www.ebay.co.uk

none at merc newcastle

just a thought are they saying the one next to your egr is faulty? if so the one above is correct.

If i put the number you have stated in it gives me this part with autodoc which is down on the throttle body pipe

https://www.autodoc.co.uk/car-parts/oem/a0061531528

which sensor is the issue??

Knowing how bad your egr was I would definately change the back pressure sensor out

Apologies.. I added an extra 0 to the
The number I quoted


This is the part itself

I have asked Admin to edit my error.

 

[DSM10000]

Genuine Mercedes Benz OM642 Engine Exhaust Back Pressure Sensor A0091535028 | eBay

Part Number A0091535028. Fair wear and tear and parts fitting incorrectly are not covered under this warranty.

www.ebay.co.uk

This has a different part number to the sensor in my vehicle.

Did MB change the part numbers or is this for a different version of the OM642?

 

[DSM10000]

Just to update.

The car has been showing an EGR error (several related codes) for awhile.

Unplugging the EGR connector would result in a EML warning. Plugging the EGR connector in would turn out the warning light but result in a Limp mode with the engine reluctant to go above 2000 rpm a
with limited performance.

Since a new EGR valve was fitted (Pierburg) the EML is no longer lit and the engine response was much better.

However, at low rpm (1200 to around 1800) the engine would "hunt" and be less than smooth.

Removing and cleaning the back pressure sensor briefly cured this but the hunting etc soon returned.

Unplugging this sensor has restored the smooth running again although a little down on power (no EML) and a little slower to boost.

To me this points to the back pressure sensor being faulty.

This part is currently on back order with MB but with no date for UK delivery.

As shown in my link above is there are a number available on eBay but with different part numbers to the one on the sensor fitted to my engine.

 

[unclebuck]

which om642 is in yours? mine is the om642.920 there were upgrades to the sensor the original had a different number in mine but the epc shows the upgraded versions

 

[DSM10000]

which om642 is in yours? mine is the om642.920 there were upgrades to the sensor the original had a different number in mine but the epc shows the upgraded versions

It's in a 2008 W211.

The 221 hp version

 

[DSM10000]

With gratitude to "unclebuck" who very kindly looked up the latest part numbers on EPC I was able to find an Exhaust back pressure sensor from Mercedes

I fitted this but the misfiring and "hunting" remain.

These symptoms first appeared after replacing the Turbocharger actuator with a rebuilt unit last year,as soon as the actuator was fitted and on the way back home the car was very jerky and unpleasant to drive.

A scan at the time showed a fault code related to the EGR. This was cleaned and lubricated and went away for a while but returned.

Unplugging the EGR would restore smooth running but with a drop in performance in terms of boost being a little softer

Plugging it back in would see the car go into Limp mode with very limited performance.

The EGR has now been replaced with an OE Pierburg unit and all fault codes have now gone and it doesn't drop into Limp mode anymore.

However the car also went back to being hesitant and jerking at low rpm straight away so I checked the Exhaust back pressure sensor which seemed blocked. I cleaned this but with no change so I replaced it with a genuine MB part , again with no change.

Unplugging the back pressure sensor stops the hesitant and jerky behaviour and the car is then drivable but it is noticeably less responsive.

I have an iCarsoft MB 2 unit which shows no fault codes when all sensors are plugged in so I would be very grateful for any suggestions of what I might check in terms of live data etc

My Independent wants to replace the Turbocharger but will only fit a genuine MB supplied unit and well over £2000 fitted this doesn't make economic sense on a 2008 car that has covered 160k even though it has a fresh 12 month MOT.

I am unsure if the Turbocharger is at fault because there is no smoke and when all sensors are plugged it has excellent performance with good low speed response and no noticeable smoke just the hesitant and jerky behaviour at low (around 1200 and to 1500) rpm

When it is working it is still a very pleasant car to drive, is well equipped and in very good condition for its age but I am tempted to just sell it for spares or repair as it is getting frustrating not being able to find a definitive answer to the problem.

Thanks in advance for your help and suggestions.

 

[W1ghty]

What about spraying a can of turbo cleaner through the front of the turbo when the car is running ?
You could also try putting the resistor fix into the inlet port motor to see if that makes a difference?

 

[DSM10000]

What about spraying a can of turbo cleaner through the front of the turbo when the car is running ?
You could also try putting the resistor fix into the inlet port motor to see if that makes a difference?

Certainly things to think about...... Will it run with the inlet pipe removed?

Also, if it was the inlet port motor would it not show a code?

 

[W1ghty]

Certainly things to think about...... Will it run with the inlet pipe removed?

Also, if it was the inlet port motor would it not show a code?

If you pull the pcv small orange seal out slightly from the side of the batwing , you can poke the thin tube that comes with spray cans into here without triggering codes .

as far as the inlet motor with faults , I’m not sure on the codes . I only say this as a cheap option for the diy’er because the ilps motor, turbo,back pressure sensor and I think the egr all share the same fuse so maybe a fault on one knocks onto the others , but I’m just guessing here .

 

[DSM10000]

If you pull the pcv small orange seal out slightly from the side of the batwing , you can poke the thin tube that comes with spray cans into here without triggering codes .

as far as the inlet motor with faults , I’m not sure on the codes . I only say this as a cheap option for the diy’er because the ilps motor, turbo,back pressure sensor and I think the egr all share the same fuse so maybe a fault on one knocks onto the others , but I’m just guessing here .

That's good thinking.

 

[unclebuck]

message sent, have a think

 

[W1ghty]

message sent, have a think

What , you are going to sell him your newly fitted turbo attached to your CLS

 

[unclebuck]

What , you are going to sell him your newly fitted turbo attached to your CLS

Lol nope

 

[unclebuck]

Offered to help him out, drive down if need be with my tools etc.