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      03-03-2012, 04:09 AM   #49
ca2del
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United Kingdom
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Drives: 2007 330D, 1978 1275GT
Join Date: Jun 2010
Location: Cambridge, UK

iTrader: (0)

Hopefully this'll be the final update from me regarding my DPF :-)

So, in short, I'm now very confident that the issue is now fixed, and the DPF is as 'clean' as it needs to be to perform active regeneration when needed.


Firstly, here's what I've learned:
  • Fault code 480A is caused by increased backpressure at DPF. Once this fault is logged, the DPF will NOT attempt regenerate. It will also abort any regen currently ongoing.
  • Fault code 481A is caused by significantly increased backpressure. Once this is logged, the iDrive or OBC will log "Particle Filter! Possible to continue journey..." This will reappear within 10 minutes of engine being switched on, provided 481A is present.
  • Exhaust temperature must be 200'C for any regeneration to be attempted (this cannot be checked via OBC)
  • A speed of 40mph (in 5th) is sufficient for an active (self) regeneration.
  • At 40mph, on a level road, fuel consumption will be significantly increased during regeneration (for example, from 50mpg before regen, to 30-35mpg during regen - as displayed on swing-meter)
  • A DPF cleaner (additive) will help the DPF regenerate. It lowers the exhaust soot burn-off temperature from ~450'C to ~200'C, meaning the filter may begin to burn off soot even under normal driving conditions.
  • A DPF cleaner (additive) will not solve a DPF warning on it's own. Once the cleaner has run through the system in a tank of fuel, the car must be able to regenerate. Otherwise you are back to square-one.
  • The amount of fuel in the tank must be above a certain level. Some say 10ltrs, in my experience this was more like 40-50ltrs)


Here's what I did, this morning.
  1. Drove for 20 minutes at a normal pace, to warm the engine to >75'C
    • "Particle Filter!" warning appeared.
  2. On a quiet A-road, I began driving at a steady 40mph (cruise control set)
  3. Read fault codes;
    • 480A, 481A present.
  4. Cleared codes
    • 480A appeared within 10 seconds.
  5. Cleared codes
    • MPG dropped from 50 to 30 immediately.
    • 480A appeared within 20 seconds
    • MPG returned to 50MPG immediately.
  6. Cleared codes
    • MPG dropped from 50 to 30 immediately.
    • 480A appeared within 40 seconds
    • MPG returned to 50MPG immediately.
  7. Cleared codes
    • MPG dropped from 50 to 30 immediately.
    • 480A did not reappear
    • After 15 minutes, MPG returned to 50+

I drove for another 30 miles, and 480A did not appear. Fuel consumption has gone from an average of 35-40mpg (displayed on iDrive) to 54mpg.

I think it's over...

Last edited by ca2del; 03-03-2012 at 04:29 AM..