W204 - Power Loss

[dj0nes]

Hi Guys,

I'm having some real issues with my car at the moment I'll try and summarize it as quickly as I can below.

2010 Mercedes C250
85k FSH
Remap: Angel Tuning
Otherwise standard.

When I was driving today the check engine light came on so I scanned it with my OBD reader and got this error "P0546 - Exhaust gas temp sensor circuit high bank 1 sensor 1".
Me being the optimist I assumed it was just the sensor that needed replacing so I went to Mercedes this evening and picked up a new one, fitted it this evening but the fault code is still there.
Looking at the live data it's showing the upstream temp of something like 860c which is way out of parameters.

A bit of background, I have had DPF issues in the past and had to have a cleaning agent in it (3 or so month ago) to unblock it.
Since I have had it remapped I see a light misting of black smoke under acceleration.
Sometimes under heavy acceleration at high speed there was slight blips of hesitation.

Now the power loss I am experiencing now isn't the classic limp mode as I've had had that before my car can still rev past 3k at the moment I can take it right to the red line but it feels so sluggish almost like the turbo isn't boosting.

No other error codes have come up I am at a loss as to what it could be. My mechanic says it could be remap related as when he revs the car in situ the fuel rail pressure goes out of parameters now and then too almost like it's asking for too much fuel.

So to summarize the car drives fine, smooth with no hesitation at all only it feels like it's running about 150bhp no other fault codes other than the P0546 which we cannot clear.

Any ideas guys?

 

[sirius9]

Get it plug into STAR and save the guessing games.

 

[dj0nes]

This was on STAR I believe, well a STAR equivalent.
The exhaust gas temp was reading out of parameters after replacing it with a new one it was coming back at something like 850c.

 

[dj0nes]

I had it on diagnostics again yesterday at a Bosch service centre and the guy believes it's the DPF due to the readings on live data (I didn't tell him about my issues with the DPF in the past so he came up with that off his own back)

I am thinking about doing a DPF delete. I am actually going back to Angel Tuning tomorrow for them to have a look too - I was wondering could I not just get them to code the EGT sensor out completely (Which if I get a DPF delete I'll have to do anyway) to see if that fixes the issue? Bit of a bodge job way of fixing it though I suppose.

 

[ernie]

No direct knowledge, but I'm sure I've read somewhere that the is no point in trying to tune this engine any further as it is already at its limit. Remember there are 200 and 220CDis; yours is at the top of the pecking order!

Somebody might correct this if I'm wrong!

Ernie

 

[Headhurts]

Now I freely admit to little technical knowledge but I have read on a few threads that Star will show up far more than a generic reader which may just point to a general area.

Star may well take you to the exact issue.

Good luck.


Sent from my iPad using Tapatalk

 

[steveq]

This was on STAR I believe, well a STAR equivalent.
The exhaust gas temp was reading out of parameters after replacing it with a new one it was coming back at something like 850c.

Hi,

I had the same P0546 fault code on my W204 C220 CDI.
I replaced the Exhaust Gas Temp Sensor (the sensor fitted into the exhaust manifold) -- with much trouble, I might add.

When that was done the fault code went (well I cleared it and it hasn't come back) and the orange engine warning light is off.
The OBD II reader now shows temp values at that sensor of between 120 - 140 Deg C.

850c seems to be very high -- is yours correctly fitted?

 

[Ninja997]

Same temperature problem

I currently have the same problem as you guys with the P0546 fault code

If I may ask @steveq could I get the part number from you and some general information regarding your part. Where did you get your part from and roughly how long did it take you to replace yours as you've mentioned it being very troublesome.

 

[steveq]

Hi,

I suggest that you use an OBD II scanner to delve into the issue further. I use an Carsoft i980 but others will do the same thing I assume.
That should tell you the actual values of the Exhaust Gas Temp Sensor as the car gets up to normal working temperature. My old one seemed to be permanently stuck at one value.

Is your engine the OM651?
If so then you have to remove the air filter housing to get at the exhaust manifold. To do that you have to remove the cables attached to the ECU, the air intake hose and the turbo intake hose.
Then you can see the temp sensor attached to the exhaust manifold.
That is easy to remove (easing oil helped) but the cable attaching it to the wiring loom is routed around the front of the engine and requires very (very) nimble fingers to remove, disconnect and replace.
I ended up doing it twice (don't ask) and now could do it reasonable quickly.
If you do undertake the job yourself note that the temp sensor fits into a hollow bolt which, in turn bolts into the exhaust manifold. On mine the hollow bolt unscrewed with the sensor.
Not a real problem but make sure that you unscrew the hollow bolt from the old sensor (may need to clamp in a vice) and screw the new sensor to it before refitting the entire to the manifold (the sensor can actually screw straight into the manifold without it but goes too far in without the hollow bolt) --- it will be more obvious when you see it all in situ.

I bought it from a Merc main dealer -- slightly dearer than I could have got it online but they were able to get it the same day.
I will have a look for the part number later this evening.

 

[steveq]

Hi,

I am 90% certain that the part number is A008 153 2228.
If you go to the MB dealer with your VIN they will give you the correct part.

The job took 3 - 4 hours the first time as I was very unsure how to remove the air filter housing, the cables and the pipework. The sensor itself is easy to fit but putting the cable in place and connecting it is very fiddly.

Like all these jobs, if I was to do it again it would take less than half that time.

 

[khurram]

Hey steve. Can you not fit the part from the bottom of the engine

Hi,

I am 90% certain that the part number is A008 153 2228.
If you go to the MB dealer with your VIN they will give you the correct part.

The job took 3 - 4 hours the first time as I was very unsure how to remove the air filter housing, the cables and the pipework. The sensor itself is easy to fit but putting the cable in place and connecting it is very fiddly.

Like all these jobs, if I was to do it again it would take less than half that time.

 

[steveq]

Hey steve. Can you not fit the part from the bottom of the engine

No, it is bolted into the top of the exhaust manifold -- only accessible from the top (unless you have triple jointed, paper thin arms).

The removal of the air filter housing and the cables isn't too much work.
The fiddly bit is getting the cable into place.

 

[Jimmas]

Possibly a blocked DPF, that could cause the system to have to much back pressure and a rise in exhaust temprature, the back pressure would cause lack of power.
As said get it onto a star machine for more in depth analysis.

 

[khurram]

No, it is bolted into the top of the exhaust manifold -- only accessible from the top (unless you have triple jointed, paper thin arms).

The removal of the air filter housing and the cables isn't too much work.
The fiddly bit is getting the cable into place.

is there x2 exhaust gas temp sensors. one top one bottom maybe. because i was advised on another forum that you do it from the bottom. i just went into mercedes and asked for a exhuast gas temp sensor. came with a diagram stating its on the middle top ish of the exhaust manifold. is this correct. would you mind breifly explaining how to do it.
thanks

 

[grober]

If the remap has changed the EGR VALVE settings that would certainly alter your exhaust gas temperature- by how much I'm not sure.
http://autocats.ws/manual/sdmedia/mediadb/mb_Acrobat/einf/204/einf_br204_cdi_OM651__en.pdf

 

[khurram]

No, it is bolted into the top of the exhaust manifold -- only accessible from the top (unless you have triple jointed, paper thin arms).

The removal of the air filter housing
and the cables isn't too much work.
The fiddly bit is getting the cable into place.

My car is a 2011 c250 saloon.

 

[steveq]

Hi,

Here is a picture of it:-

It is the long piece of metal with the wire attached. You could probably find better pictures yourself by googling mercedes OM651 exhaust manifold.

There is more than one sensor but that is the only one that is 'upstream of the turbo' which is what was reported as the fault.
It is possible to see it without removing the air filter housing but I had to remove everything to get a spanner on it.

It might be possible to get at it from underneath but it certainly didn't look like an option when I did mine.

 

[khurram]

Hi,

Here is a picture of it:-

It is the long piece of metal with the wire attached. You could probably find better pictures yourself by googling mercedes OM651 exhaust manifold.

There is more than one sensor but that is the only one that is 'upstream of the turbo' which is what was reported as the fault.
It is possible to see it without removing the air filter housing but I had to remove everything to get a spanner on it.

It might be possible to get at it from underneath but it certainly didn't look like an option when I did mine.

Mine has EML light on. Loss of power and says p0546 code. Exhaust gas temp sensor 1 high

 

[steveq]

You may well be correct and that is your problem. I understand that it does frequently fail and replacing it resolved my issue.

I suggest that you use an OBD II scanner to check the temperature sensor values when the car is cold and then up to normal working temp.
On mine the values were permanently stuck at 250degC.

I described how to fit it in a previous post on this thread.