N57 DPF on 2014 535d @ 40k miles

fmorelli

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Just got it back from the dealer. Interesting story. Various codes since early summer. First they replaced the NOx sensor, then 3 weeks later another CEL and they replaced the 02 sensor - both of these sensors are mounted behind the DPF. I told the diesel tech that, at 40k, it was like winning the lottery (those two sensors don't die in 40k miles). Couple weeks later ... another CEL. Yep ... so they did the Diesel Particulate Filter. That's about a $4k+ job, including new temperature sensor on the DPF, various hoses, and a subframe drop to do the install.

But it gets better. Dealer tells me it is not under warranty but BMW decided to pay it on Goodwill. Waaaaaa? I don't believe it. Not covered by CPO he says. I ask about emissions warranty. Not covered, he says. So I call BMW NA. They tell me only certain states have emissions warranty. Waaaaaa?

So I go digging ... of course find BMW limited warranty - right there, DPF covered by federal emissions 8 year / 80k miles. Call back BMW NA with a link to their own warranty docs ... WTF. They are confused at the responses and open a case.

It's paid for mind you, but I'd like this to be sorted out ... and my dealer has been good to me, want to make it clear this is a warranty repair on BMW NA and not them.

Why did the DPF fail? Not sure. Wondering what the regen history is. Don't know if the DDE keeps a history. I've read that a faulty engine temp sensor can prevent regens from happening. Makes no sense that a DPF filter fails in 40k miles.

Filippo
 

fmorelli

Lieutenant General
Staff member
Aug 11, 2017
3,638
3,431
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55
Virginia
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E89 Z4 35i, F10 535d
So 2014 manual, warranty does not asterisk "catalytic converter", which otherwise identical text in 2018 manual asterisk states that on the diesel the DPF is the catalytic converter. On that basis, BMW NA says they are not responsible for the DPF (but did a courtesy replacement). I suspect this would not hold up in court, if someone brought them to court. Of course as long as they are paying, they'll never be taken to court.

Second thing I found out - BMW calls it the Diesel Particulate Filter/Catalyzer ... that's because the pipe actually has two distinct parts - a particulate filter and an oxidizer. The latter is an actual "catalyst". But it is built as one unit.

Filippo