Exhaust gas temp sensor question

sliver

New member
The engine check light lit up in my 2008 NCV3 a few days ago while on a trip. It remained on after several start cycles so I planned on taking it to the Dodge dealer upon our return home. The morning I set out for the dealer, the glow plug light came on and stayed lit for a short time after starting the engine. The dealer service department ran the scan and told me the stored codes indicated an open glow plug circuit as well as an older code event from the exhaust gas temp sensor (or did he say EGR temp sensor? - I forget). They replaced the #3 glow plug under warranty and cleared the codes.

This Sprinter had 11,000 miles on it when we purchased it, and 14,500 miles on it now. I have quite a bit of experience with gas powered vehicles, but I'm in the learning phase when it comes to diesels. I'm curious as to what the exhaust temp event might have been about, and what, if anything, it might have to do with the glow plug failure? The service guy said he wasn't sure why the temp event occurred, only to wait and see if it comes back.
 

Vander

Sprinter Tech
The EGT sensor is used to tell the CDI modual the temp of the egr going into the egr cooler and leaving the cooler, something gas engines do not have, that way it knows the temp of the egr gases intering the intake manifolds. For some reason the EGT sensor saw a temp value that did not match it's calculated (ok temp ranges). If it is not active now Just wait for it and see if it comes back, may just be an intermitant thing. A number of things could cause an incorrect temp value. Only one glow plug out will not effect the EGT readings, the glow plugs like to stop working a lot on the sprinters when they get carboned up.
 

sliver

New member
The engine light came on, then like two days later, the glow plug lamp came on so I had to wonder if there was a connection. I don't have a code reader though, so for all I know the engine light was on for the glow plug and the EGT event was sometime in the past. Is there an EGT sensor for the intake side and one for the exhaust side of the cooler? I believe the code that was set related to the exhaust side.

When I took it in I was thinking this was probably the start of an EGR failure, so I was a little surprised to find out there was no EGR problem (yet).
 

flattop9119

New member
There is a few exhaust temp sensors. Possible when your vehicle was doing a regen the desired temp wasn't reached. It does use the glow plugs to raise the exhaust temp to the desired level to do a regen so maybe just that. Just keep an eye on it for now if light doesn't come back on then no worries.
 

thlevy48

New member
I also have an '08 (3500, long, tall) that keeps getting an exhaust temp sensor code (P0544). It happens if I forget to let the glow plugs cycle when starting, no matter what the outside temperature. I just clear the code and wait for it to come back, sometimes its several days, other times it is several weeks.
 

Vander

Sprinter Tech
I also have an '08 (3500, long, tall) that keeps getting an exhaust temp sensor code (P0544). It happens if I forget to let the glow plugs cycle when starting, no matter what the outside temperature. I just clear the code and wait for it to come back, sometimes its several days, other times it is several weeks.
It sounds like you have something else going on with your van, could not begin to suspect what though without a computer to check it out, either your temp sensor is being over sensitive or for some reason your exhaust is not reaching the correct temp.
 

thlevy48

New member
It has been checked with a computer and they can find nothing. I suspect that it is an oversensitive sensor. I was told that they could replace the sensor but they really didn't think it was necessary.
 

mofo989

Member
I have the check engine light gone on two separate occasions recently. The dealer attributed both to the EGR Temp Sensor. They replaced it the first time, and this time they said the sensor voltages all match what is "Expected" according to the MB trouble shooting flow chart. So they just reset the check engine light. What I don't like about this is that once the vehicle is out of warrantee then I'm paying to take the van to the dealer for stupid check engine light problems that they can never diagnose and fix (and maybe don't even matter!)
 

lindenengineering

Well-known member
Guys
Obviously I can't comment specifically about each and every CEL incidence, as I would need scanner to do that.

However as a generalization don't overlook threshold voltages into the vehicle operating systems.

No matter what the vehicle I am looking at, this is one of the first point of reference. The Sprinter is notorious for "cooking" the main circuit Y cables and if left unattended to it will "cook" an alternator. With corrupted voltages around 12.1 and 12.4 volts the control systems will have a hissy fit and throw erroneous CEL codes all day.

The voltage should be at least 13. to 14.1 to make everything jive.

The other is the exhaust system itself. It must NOT LEAK!
All the way from the turbo out to the tail pipe any leaks before after the particulate filter will corrupt the temp sensor signals and throw erroneous codes and not allow the exhaust system system to re-gen (de-soot).
These two salient items should always be carefully examined before condemning a system or sub section.
Dennis
 

Top Bottom