om642 exhaust temp sensor

[hmang]

Morning all .
It's been a while .

here goes , My w221 s350 cdi bluetec with om 642 is showing exhaust temp sensor upstream of turbo is shorted to ground or closed circuit ( para phrasing there ) .

if i clear the code , the engine light stays off until i turn the engine off for more than few minutes then it comes back .
Ive also got a clogged dpf fault showing

Found the sensor , it's the one with a 90 degree bend , attached ( seized in )to the turbo .
I cleared the codes and disconnected the strange looking connector expecting the fault to change to open circuit , but it is the same .

I read somewhere about a Z connector on a different model .

any help welcome .
thanks
Phil

 

[Botus]

not sure I follow exactly what you are saying....
If the sensor is faulty it will play up so it needs to be changed.

so if one is available that's a good starting point, whilst many others can be bodged about to lie one is there, I'd be surprised if one attached to the turbo wasn't doing a vital job of making it run correctly

a picture of the affected part and the exact fault codes would be a start? And yes if its bolted into the turbo body for 10 years at almost melting points its not going to come out easily, but doesn't mean it can't be done... usual stuff, lots of plus gas for a week, the right tools then get it very hot before trying and if it snaps carful extraction without allowing debris to go in the wrong places.

must be loads of garages that have done it

 

[hmang]

not sure I follow exactly what you are saying....
If the sensor is faulty it will play up so it needs to be changed.

so if one is available that's a good starting point, whilst many others can be bodged about to lie one is there, I'd be surprised if one attached to the turbo wasn't doing a vital job of making it run correctly

a picture of the affected part and the exact fault codes would be a start? And yes if its bolted into the turbo body for 10 years at almost melting points its not going to come out easily, but doesn't mean it can't be done... usual stuff, lots of plus gas for a week, the right tools then get it very hot before trying and if it snaps carful extraction without allowing debris to go in the wrong places.

must be loads of garages that have done it

thanks for the reply

Here's what's happening .
car is w221 s350cdi blue tec 2013.

engine light is on , but car runs ok .
if i turn off engine light , it will stay off until i turn off the ignition and restart the engine .

star diagnostic shows a fault with 'exhaust temp sensor up stream of turbo short circuit to ground ' this refers to b19/11 sensor
here ...
https://f01.justanswer.com/MASTEROFMASTERS/affb5697-3ab5-4048-85b4-c351ab03f710_b19.pdf.

on the understanding that the sensor was shorted / faulty ,i disconnected it at the block connector ( 2pin ) .and re tested
I expected the fault to change from short circuit to open circuit since the sensor was no longer connected .

the fault remained the same .
theres a couple of wiring /voltage test described in the star procedure but i dont have the relevant wiring adapter .220 589 00 99 37 .

i can dig into the wires but im asking here before i do anything rash

 

[ajlsl600]

Did you clear the existing fault before you diss connect the plug? And rechecked fault codes.
Note all faults. Before clearing

 

[hmang]

Did you clear the existing fault before you diss connect the plug? And rechecked fault codes.
Note all faults. Before clearing

Yes .
sorry forgot to say i cleared the faults down

 

[Botus]

that looks like the "back pressure sensor"

the WIRES are a fantastic design and can easily get trapped by the engine cover
they have a big silver heat shield sleeve and they can be mangled inside that

the sensor dies at 9 year mark and 100k mile and shows in live data with a high hPa reading with the engine OFF

it should be as flat as hell without that working?

check here https://forums.mercedesclub.org.uk/...-motor-delete-cdi2.97061/page-14#post-1868316

 

[hmang]

that looks like the "back pressure sensor"

the WIRES are a fantastic design and can easily get trapped by the engine cover
they have a big silver heat shield sleeve and they can be mangled inside that

the sensor dies at 9 year mark and 100k mile and shows in live data with a high hPa reading with the engine OFF

it should be as flat as hell without that working?

check here https://forums.mercedesclub.org.uk/...-motor-delete-cdi2.97061/page-14#post-1868316

Confused now
Star says it’s a temp sensor and the car drives fine

the silver turbo heat shield is well clear of the wires

I haven’t chased the main loom back yet looking for trapped pinched wires

 

[Botus]

it can get squashed within 3 to 6 inches of the sensor (the engine cover snags it on a bracket if you don't check when fitting the cover)

I guess depends on the turbo.... in the link where I'm rambling about the back pressure sensor, a few posts above is a photo.... that's what they had on the 3 litre V6 diesels from 2005 onwards. The sensor in that link gives info to move a bit in the turbo changing the flow hitting and spinning up the turbo "vgt".... bit like fine tuning the flow on to a water wheel...

strange wondered how variable vane turbos do it... but so far only found its the same thing ???

Knowing the exhaust temp would be to allow the engine management to do something, so you ought to be missing out on something...

 

[Botus]

https://forums.mercedesclub.org.uk/...sensor-p2080-merc-w204-c250-cdi.172975/page-2

 

[hmang]

https://forums.mercedesclub.org.uk/...sensor-p2080-merc-w204-c250-cdi.172975/page-2

Thanks I’ll have a proper read of that link