How do I repair the DPF problem on my BMW?

QUESTION

Hi John,

I have a 2009 BMW X5 E70 3.0d that started showing some issues that seem to be related to the DPF and losing power randomly.
Before taking (again) my lovely X5 to a local workshop to be (hopefully) fixed, I thought I could chat a bit about it with someone that is (1) neutral and (2) most important, really knows about car stuff and might be willing to help me not being robbed (again) by the workshops.
Got a Carly dongle and the mobile phone app and the subscription for looking a bit more into what's wrong with this car but my experience is less than average with it... so far.
Anyway, willing to pay for the favour, if I am lucky I will pay for your advice less than I will pay for dealer/workshop "advice" and "recommended repair" :)

Please let me know if you're interested to talk further.

Thanks

Kind Regards
JL

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ANSWER

Hey John,

I’d like to help you, but I’m a mechanical engineer, not a BMW master technician. With a 12yo car there could be any number of components which have failed (or are working only intermittently) that contribute to this problem.

For example, there could be a leak in the compressed part of the air intake (after the turbo and the MAF sensor) and if that’s the case it’ll cause the vehicle to over-fuel, and this could cause the DPF to clog early and/or fail to regen. There’s a differential pressure sensor across the DPF which tells the computer what the soot load is. If that fails, the computer makes poor decisions about regenerating…

Without a skilled person going ‘hands-on’ with the car, it’s all just speculation. You’re essentially up against the 2nd law of thermodynamics, the only countermeasure for which is the engagement of diagnostic skill, which involves work and money.

Choosing the right dude to do the diagnosis is going to be critical. An experienced independent BMW technician is the guy you need (I’m neither of those things).

All the best with it.

JC

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