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UK Tech.
UK Tech., UK Car Mechanic
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Experience:  BMW Technician.
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I have an E60 525d SE, 48,000 miles. Symptom loss of power

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I have an E60 525d SE, 48,000 miles. Symptom = loss of power under load. Initial diagnosis by BMW Dealer = regenerate Particle Filter (£300). No effect. Second diagnosis = replace Particle filter (£1,500). No effect, because third diagnosis = the CAT has gone as well, needs replacing (£900)........ In your experience how likely is it that the DPF and the CAT would both fail at the same time ???



do you have any information on which fault codes where stored in the memory or if any warning messages were displayed in the instrument cluster?




Customer: replied 7 years ago.
day before problem started a yellow warning light came on briefly (looked like upside down yellow light bulb with an exclamation mark in it - can't find that in the owners manual so don't know what it meant). Couldn't find any messages when I pressed "check". The lack of power problem started next day - but no warning messages. When the car had been to the BMW dealer and they had tried to regenerate the DPF - then got a warning light - looks like a yellow helicopter - to do with emissions ??
Customer: replied 7 years ago.
is(NNN) NNN-NNNNa fault code
B132_D5CSF ??

I am also uneasy about the fact that when I asked for the old Particle Filter that had been replaced, I was told that I'd have to pay more than £200 surcharge to keep the old, "broken" one - because the Dealer had to return it to BMW. Does that sound right ?

It's going to be tricky to analyse their diagnosis without information on the fault codes or details on why the technician came to these conclusions.


The first diagnosis is perfectly viable. A clogged DPF can lead to a lack of power. But a clogged DPF can also be identified by monitoring the readings obtained from the engine's exhaust back pressure sensor. The technician should have taken note of these readings prior to the regeneration and then compared them to the readings obtained post regeneration. Only when comparing these can the DPF be replaced. It may even be necessary to attempt to regenerate the DPF more than once.


If it is then deemed necessary to replace the DPF (which isn't as common as most people might think) another back pressure sensor test should then be carried out to confirm that this was infact the original problem.


To then go on and say that the catalytic converter is the actual problem or part of the problem sounds a little like clutching at straws to me. A failing or blocked cat can be identified by monitoring the status requests of the various engine sensors via the testing equipment. Overall, i find it unlikely that both components have failed at the same time, unless the vehicle is very mileage.


What are the exact symptoms of the power loss please? When accelerating from standstill, under kickdown, when slowing and then accelerating away quickly etc?




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Apologises, i've just noticed the mileage which is quite average so makes it even more unlikely. I hope that they are submitting a goodwill claim to BMW on your behalf dude to this and the age of the vehicle.


There will be a surcharge on the old DPF but even if you were to examine it there wouldn't be alot to see, but a comparison between the weight of the old one and the new one can give an idea of the amount of soot trapped inside.