W212 (OM642) Exhaust gas temperature sensor

[Screechy]

I've had error code P0546 on my 2011 E350 cdi, it's appeared twice so am looking to replace the EGT sensor. Does anybody have an installation guide or picture so that I can be sure I'm looking at the correct sensor?

Had a search and sounds potentially quite tricky to access so ideally I know what I'm looking for before I start disassembling engine ancillaries!

 

[steveq]

Hi,

I replaced the Exhaust Gas Temperature sensor on my 2011 C220. It is tricky with a bit of disassembly required but not too bad.

Yours is a different engine -- a V6 I think. That will have a sensor on each exhaust manifold.

Have you an OBD II reader?
That should tell you which one is giving the fault code.
That should also tell you the temperatures they are reading. Look at them when the car is up to normal operating temperature and when it is cold. They both should read the same temp.
Also, they should both be showing the ambient temp when the car is cold. When mine was faulty it seemed to permanently show 250degC.

You could also clear the fault and see if it comes back.

 

[Screechy]

Thanks. Borrowed a OBDII reader and cleared the error but it has returned. I don't have a reader capable of getting readings at the moment.

P0546 is high bank 1 sensor 1, which I think means is driver side in the manifold.

I'm really after a guide on what needs removing.

 

[steveq]

I would suggest that you do a bit more analysis before you start replacing parts.
I understand that a blocked DPF can give the same symptoms/errors.

A good Mercedes focussed OBD II reader will probably cost less than the sensor -- it is worth checking the temp of that sensor over time in various conditions/situations. You have 2 so it will be easy to compare values.

In terms of replacing the sensor -- on my car it is bolted directly into the exhaust manifold. To get at it I had to remove the air filter box and that also entailed disconnecting the ECU wiring. Yours may not have the ECU attached to the air filter housing. On the other hand, being a V6, the engine bay is probably even more cramped.

 

[Screechy]

Ok so changed the sensor on the driver side today and error came back intermittently. Unfortunately I bought the sensor before the advice above. I also had an error message p0428 (cat sensor temp) but not sure where that sensor is. Not really sure where to go next

 

[steveq]

Hi,

I'm not sure I understand when say that the "error came back intermittently"?

I still think you need to analyse the issue more thoroughly. Your own Mercedes biased OBD II reader will pay for itself very quickly.

The new issue may be just coincidental but could be related and something else is actually causing the errors.

Maybe a session on Star with a good Indy is worthwhile before replacing more parts?

 

[Joesoap17]

both faults pointing at temp in the exhaust, don't buy anything else, other than a diagnostic tool which van read those temps, until you know what is causing the problem!!
Good advice to try an indie, but if you feel you are confident and will benefit from having your own diagnostic tool invest in that first.
I am not sure if an Icarsoft MB2 reads those types of data but are around £150 cost of 2-3 diagnostic sessions depending on where you go?

 

[Screechy]

I've now got the Icarsoft v2 and the P0546 code is there. I can't see the live data for that sensor but I've asked for technical help from Icarsoft. I can clear the message but it returns when restarting the vehicle

 

[Screechy]

With a bit more understanding of the reader I found code b19/11 which can’t be cleared. So that’s the temperature sensor upstream of the turbo which the reader says it’s shorting. Is it worth trying to clean the sensor? Or a terraclean? Or just replace it?

 

[steveq]

Hi,

I doubt if cleaning it will make any difference. That sensor is being cooked by the very hot exhaust gases when the car is running. Thinking about it, I am surprised it lasted the 5 or 6 years that it did !!

Your Icarsoft should show you the actual values of that sensor.
On my iCarsoft i980 (different model to yours must must have some similarities), this is what I do to see the values:-

Select Diagnose
then Benz
then select your car -- E Class 212
then select your exact model
then select right hand drive & auto/manual
That will show you all the various sections of your car that are available.
Select the first one on the list which is CDI Motor Electronics 'CDID2' for combustion engine 'OM651'(N3/9). --- Note :- Your engine is different but the option is probably much the same.
When I go into that on my car I see :-
Control Unit Version
Read Fault Memory
Clear Fault Memory
Actual Values

When I select Actual Values I see about a dozen items.
Items 6 & 7 are 'Check boost...' and 'Limitation of engine...'.
Select either of these.

On either of these the 'B19/11 Temp sensor upstream of turbocharger' is the value you want. Scroll down to see this if it isn't on the first screen display.
Mine shows values varying between 135 and 167 Deg C.
When the engine is completely cold it shows the ambient temperature -- (much the same in the current heatwave !!??!!).
You have 2 so you have something to compare the values to.

When the sensor was faulty on my car it permanently showed a value of 250degC.

 

[Screechy]

Thanks for your help. Read the live data and temperature was at 350 deg C.

Ordered a new sensor and will see what that does.

 

[steveq]

Hi,
I thought that you had already replaced the sensor (Post 5 above) ?

What was the temp. value on the other exhaust gas temp sensor?

 

[Screechy]

I may be confused but the first sensor I replaced was around the exhaust manifold but the error is actually around the exhaust side of the turbo.
I’m struggling to find a diagram with the sensors on it but I think the ‘upstream of turbo’ is a different sensor

 

[Screechy]

Now found the diagram on workshop-manuals.com and it’s under the turbo. Sensor was reading 349.96 degrees, plugged the new sensor in and it’s 25 degrees. Only problem is getting to the sensor as it’s very tight down there.

 

[steveq]

Hi,
That sounds like you are looking at the correct sensor.
It should be bolted into the exhaust manifold. On mine it was screwed into a bolt that was screwed into the manifold. I suspect that the V6 is more difficult to get at compared to the 4 cylinder in mine.
Best of luck with it.

 

[lordlee]

I also have that upstream of turbo sensor reading -247 on the diagnostic tool. Does anyone know exactly where this sensor is and more importantly what the part number is please?

 

[Screechy]

It is in the centre behind the engine, under pipe work, wire trailed to driver side about 12”. It was a pig to get to. Didn’t get the part number but described tout the dealer sent me it out with the above description and the code.

 

[lordlee]

Didn’t get the part number but described tout the dealer sent me it out with the above description and the code.

Thanks for this. I tried this with Reading Mercedes earlier and they weren’t particularly helpful. Maybe I’ll go in and have the discussion. About £100 for the part?

 

[Screechy]

Yes i think I paid £99, I dealt with the Newcastle dealer via eBay even though I’m in Devon. I also had code b19/11 from the icarsoft reader which I think they used

 

[lordlee]

I bought the part from Basingstoke in the end for £86. Reading Mercedes’ service was about the worst I’ve encountered for some time so I didn’t use them.
Seems to be running perfectly again so fingers crossed that’s it for now.