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 Hoping for a little help from those more knowlegable.

Bmw E60 525d m sport 2006.

Car has recently been down on power limp mode,along with a strange exhaust smell....no warnings on dash, scanned for faults came up with

battery sensor(which I know about) and all 6 glow plugs, no other faults.

So I replaced all 6 glow plugs and the controller, did a scan just the battery sensor fault now.

Took vehicle for a long motorway run but still in and out of limp mode.

I then suspected DPF blocked my soot reading was 15g and ash mass 109g but cant be accurate as no sensors on DPF.

Exhaust gas pressure test before DPF was 1010 hPa...14psi !!!

Removed exhaust and DPF and cleaned DPF which was not too bad although a lot of gunk did come out.

While exhaust was off I started the car with just the catalyist on the down pipe, I expected a lot of noise but it was very quiet you couldn't tell 

really that the exhaust was missing...is this normal? and with my hand held over the end of the downpipe hardly any pressure coming out...again is this normal?

I put it all back together and took it for a run...no change....I now suspect the cataylitic converter maybe damaged and blocked.

Took a temperature test from the cat on my return with an infared thermometer ,at the engine end where gasses go in 250 degrees f and on the back of cat as gasses leave 182 degrees f.

Am I right in thinking the cat is not working as these temps should be the other way around? plus the exhaust fumes smell odd still.

I am assuming that due to the faulty glow plugs which must have not been working for ages, as I always had misfires on cold start and the failed regens

pumping extra diesel into the engine and not getting burnt has destroyed the cat but obviously before I go to the expense of a new cat,

im asking for a little help if I am on the right track?

Many thanks.


Edited by mexy

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The car is surprisingly quiet with the DPF and exhaust removed. I ran mine with just the cat to see what it sounded like and it wasn't that loud at all !

 However there should be a tonne of exhaust flow. Sounds like your cat is blocked - they can break up inside.


If you've had the DPF off and yours is Pre-LCi getting the cat out isn't too bad. You could leave the rest of the exhaust in place. My experience is with a 535d but it should be similar. The metal plate under the engine needs to come out. There's a 13mm nut and a clamp to the turbo. There's a rubber pipe wrapped in foil that need to be disconnected from a pressure sensor just under the acoustic cover at the top of the engine, a plug around there too. Then a couple of supporting nuts. The cat wiggles out the bottom.


The cats don't normally fail so a secondhand one might be a reasonable bet.

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