Hi. 

 

Hope to get some help with my 2010 Superb 2.0 tdi 170hp CR. 

 

Fault code is P242a EGT B1 S3, wich is the sensor before the dpf. 

 

I’ve replaced the sensor with a new one but the problem remains. 

When logging the channel in VCDS the temp is fine (after clearing the fault code) but after a minute or two the temperature rises from around 100 degrees C to maxout at 930 degrees in a few seconds. 

 

I tried the old sensor and the same symptoms as with the new sensor, so it wouldn’t be a sensor fault?

 

Done some searching but haven’t found anything usefull on the wiring harness. 

Have you checked the condition of your DPF?

No I haven’t. The other 2 EGTs and the diff. pressure sensor shows normal values. 

The car drives normal, not like a car with a clogged DPF. 

The only noticable thing except the CEL and glow lamp is that the cooling fan stays on for about 5min after I park the car, every time. 

If both sensors are showing the same temp spike and other sensors are reading normal values, it does suggest either wiring or the ECU is at fault.

 

You should test the wiring with a load lamp to confirm it can carry current properly. If you haven't already, check erwin to get the appropriate wiring diagrams.

I have heard of this sensor being taken out by head gasket failure.

 

It is the first sensor in the exhaust so gets heated by superheated steam quickly if there is a head gasket leak.

 

Just worth checking coolant level carefully.

Found the registration link to erwin on this forum and printed out the wiring schedule on the EGTs. Hope to get some time to investigate it further this weekend. 

 

There’s a sensor direct after the turbo, if it was a blown headgasket then the first sensor would show the high temp and not the second one in line?

I had similar problem with sensor on my wifes Meriva  the pressure sensor was replaced and values were correct on live Data 

It would continue to try to do a regen even after sensor replaced.


BUT I had to tell the ECU that a new sensor was fitted so that it could reset the values in the ecu.
 

Gone

Edited 9 January, 20197 yr by FlyingSpanner

Double checked the sensors earlier before I bought the new sensor and its the G495 sensor (brown connector) that’s giving me the headaches. 

 

Tried both the sensor in free air and live logged it in VCDS and both reads ambitient temp. 

 

Double checked the ground cables to all 3 sensors today and they’re fine. 

Unclipped the G495 sensor wire between DPF and connector, so it hangs in the air but without succes. 

 

Will try to check the signal wire to the ECU tomorrow to rule that out too. 

 

Is 03L906088FG the latest revision on the sensor?

Gone

 

 

Edited 9 January, 20197 yr by FlyingSpanner

Thanks for the help, so far. 

I’ll double check the live datas again, it was a few months since I did that check to get the right sensor. What I can remember from the earlier troubleshooting it put a fault code on each sensor (after disconnecting one sensor at the time). 

 

Didn’t have time to get to the ECU today but the earth wires was a quick check, just to rule them out from the list. 

 

I’ve been working with cars and electronics back in the days, fitting standalone EMS and other stuff. 

So I Think I know my way on the wiring diagrams, but not that much with the OEM VAG diagrams. 

Thanks for the writeup on the sensor wiring, printed that diagram yesterday. 

 

I’ll keep you posted as the troubleshooting goes on. 

G

Edited 9 January, 20197 yr by FlyingSpanner

G

Edited 9 January, 20197 yr by FlyingSpanner