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2006 BMW 530D DPF Regeneration Problem

2K views 2 replies 2 participants last post by  gregw2 
#1 ·
New to the forum and looking for advice. I had my DPF replaced about 10 months ago and all was well until a few weeks ago when the DPF warning light came on. Ran BMW DIS and it confirmed that the exhaust back pressure was over the limit and that the DPF was heavily sooted. There was also a fault with the IAT sensor which is integrated with the Hot Film MAF, this was showing a temperature of -50C and DIS suggested the sensor was broken or a wiring problem. I think the DPF has sooted up so quickly because the car will not schedule an active regeneration. I have enabled regeneration using DIS and requested a regeneration. I have monitored the key parameters to ensure the regeneration criteria are met: Coolant temp, Exhaust temp, speed greater than 60km/hr, at least 10 litres of fuel, but the car will not trigger a regeneration. Is it possible that the IAT fault is preventing regeneration? Initially the coolant temperature was not reaching 75C, but changing the thermostats fixed that so the only thing left seems to be the IAT issue. When I request regeneration using DIS it warns me that there are error codes in memory (IAT fault) that should be cleared before regeneration, but it is unclear whether this is a recommendation or is mandatory before regeneration will be triggered. Can anyone help?
 
#2 ·
Further diagnosed this problem by buying an oscilloscope so I could look at the outputs of the Hot Film which has an integrated IAT temperature sensor as well as mass flow sensor. The mass flow sensor out put was ok, the square wave frequency increased with revs as expected. The IAT output was stuck at 5V no sign of the expected square wave with around 10Hz frequency which encodes the temperature in the pulse duty factor. So looks like I need to swap out the MAF to clear the IAT error codes in the DDE, otherwise I don't think it will regenerate.
 
#3 ·
I had have a problem with my DPF caused by faulty thermostat. Engine never riched requested temperature. Went to recomended local garage and they trird to clean it up but only last for 20 miles. So they sugested to remoove it completely. Cost me £240 including thermostat replacement. My engine is in rated eco5 so no problem with passing MOT. It makes a smoke when I put my foot dawn but at least I saved £700 for part and God knows how much for dealer service cost.
 
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