VW Scirocco DPF light/engine management light

[Theo Hodgson]

Hey, my cars DPF light came one after one of my EGT sensors became faulty and i continued to drive the car, eventually resulting in the car going into limp mode. I took the car to a garage and got the sensor changed and they also used some DPF cleaner and put the car through a few forced regenerations for the DPF, eventually leading to 0g of soot build up in the DPF, however the DPF light and engine management light will not go out, and the car is still in limp mode. All sensors are working as they had it on a live feed to show they are all doing what they are meant to and as there is no longer any soot build up i dont understand why the warning lights and limp mode wont go out, any suggestions?

 

[Burnerman]

Im wondering if the cleaning firm actually measured the back pressure in the dpf? Cleaning them, although popular, isnt always a guaranteed cure.
The fault codes should be read and then cancelled.....it sounds like yours are coming straight back.
John

 

[Theo Hodgson]

I didn't get it terra cleaned or whatever it's called, it was just some DPF cleaner that you put through the filter which allows the soot to be burned off easier. The codes clear off of the diagnostic machine but come back on as soon as the engine is started.

 

[Burnerman]

Whilst at risk of stating the bloomin’ obvious, it seems like the dpf is still blocked.....the only real way to diagnose is to interrogate the differential pressure sensor of the dpf, which measures pressure in and pressure out.
Wondering if you noticed any smoke, smell or a different exhaust noise recently?
John

 

[Theo Hodgson]

I think that is probably the case, was just checking if anyone knew something i didn't, as the soot content is at 0g and the ash is at a normal level too so it seemed unlikely to me that it was still blocked. Going to get the system flushed through and cleaned properly tomorrow, if that fails looks like i'm just going to need a new DPF! Don't think my mechanic knows much about it either as it has had him stumped for 3 days now aha.

 

[Burnerman]

We’d be interested to hear the outcome Theo if you’d be good enough to post back....
Its worth checking the state of the EGR system at the same time.
John

 

[Theo Hodgson]

I'll be sure to keep you posted! thanks for your help.

 

[Theo Hodgson]

The DPF was clear but it was still staying in limp mode and the light wasn't going out. The car has had a remap, which apparently involves tricking the ecu into thinking certain parts of the engine are no longer there, such as the EGR valve, otherwise it would always be thinking there are problems with it that wern't there. However in this case there actually was a problem with the EGR valve and it was sticking partly open constantly which was triggering other sensors in the exhaust system as it was making hot spots in the exhaust. Hence why my cheap diagnostics machine and even the local mechanics diagnostics machine couldn't pick up the problem! (thank god for mobile diagnostics teams, saved me a fortune)

 

[Burnerman]

Thanks for the update Theo!
Does this mean a new egr for the car or are you going for a clean?
John

 

[Theo Hodgson]

He has cleared all codes and took it out of limp mode and no problems have recurred as of yet (done about 300 miles) but he expects they will soon. Will most likely mean a new EGR and he also recommended that I either reset the car back to standard (get rid of the stage 1 remap) or get the remap redone through him so he can make sure nothing happens like this again. He seemed to think they didn't do a proper job with the remap when it came to blocking certain things from triggering the engine management light. Not sure don't really understand it i'm just going to go with what he says!

 

[Burnerman]

Fair enough, I think... the engine Ecu can be remapped to accommodate the absence of a dpf and egrs can be blanked off - neither which I would recommend!
Have a go with Forte EGR cleaning solution if you like.....its one of the more reliable products.
John