EOBD Emission Control warning light

[magoo]

Thanks Zion for an easy to understand explanation.

Has the soot gone now (hopefully) now I have no light ?

[Zion]

They may have freed it off, or cleaned it out and  forced it to run under test with DiagBox / calibration so it's shut up for now. The soot won't be gone forever unfortunately, it just keeps accumulating. The intake and EGR will build sticky black crud till it falls over, it's the curse of the EGR. All diesels of all brands do this. Worth asking what they actually did. Maybe just cleared the codes and reset the EGR, in which case it's just a matter of time if it wasn't cleaned.

This is what they look like when gunked up: 

   

Should look like this when cleaned or new:

   

[magoo]

They may have freed it off, or cleaned it out and  forced it to run under test with DiagBox / calibration so it's shut up for now. The soot won't be gone forever unfortunately, it just keeps accumulating. The intake and EGR will build sticky black crud till it falls over, it's the curse of the EGR. All diesels of all brands do this. Worth asking what they actually did. Maybe just cleared the codes and reset the EGR, in which case it's just a matter of time if it wasn't cleaned.

This is what they look like when gunked up: 



Should look like this when cleaned or new:

Thanks again, all info is good info. They just reset the codes and egr to see if it came back on as they wouldn't have been able to look at it till late this week.

Got some work coming up, 88,000 miles so timing belt and water pump to be renewed, which seems best to do with belt I've read on here..

[PeteH]

You\re not alone, magoo - I'm dealing with the same problem, and my car has only done about 35k.

Similar story about diagnostics - three faults recorded again -

- NOx sensor heater and NOx sensor supply voltage faults recorded.
- Pre catalyst efficiency fault also recorded.

They suggested to me that there was in reality probably only one fault, and I'm now thinking maybe it's the soot accumulation on the EGR valve.  Could that be the 'pre catalyst efficiency fault'?  But using the car only for relatively short journeys wasn't thought to be a factor.  They 'turned the light off' in order to see whether the fault would recur and warned me that they expected to see me again.  Most concerning was the suggestion that rectification might carry a hefty price tag - possibly £500.

All was well for a number of weeks and the car sailed throught the MoT, suggesting there is no actual emissions problem.  Then one day the warning light reappeared.  The engine continues to run perfectly.

If the problem is actually the crud accumulating on the EGR valve, is it possible to have a dealer clean it up?  Otherwise, does anybody know if the advice I've been given re cost (suggested to be the cost of a new sensor) is anywhere near correct? 

Any thoughts and advice would be much appreciated.

Cheers
PeteH