Exhaust pressure fault cls 350 cdi amg sport

[Ian bulley]

Hi all I've been having an intermittent problem with my exhaust pressure
The car goes into restricted mode usually from cold and acceleration onto a dual carriageway.

No eml light but when read shows up fault

15fd00 the lower limit of component B28/8 (DPF differential pressure sensor) has not been reached.

If I turn the car off then on its back to normal drives like a dream.

I've had a new sensor and a new DPF fitted by mercedes. Star tester reads the car is healthy and running fine so they're now merc are at a dead end with it.

I'm really hoping someone has come across this and can point me in the right direction

Thanks

 

[alexanderfoti]

What is the actual value of the B28/8 with the engine off?

 

[Ian bulley]

Hi I'm not sure they messurd it while it was off because it looses the codes once its been switched off.
They gave me the paper work not sure if this tells you anything ?

 

[alexanderfoti]

0.02-0.00 bar at 250nm engine output...

Looks like the dpf has been bashed through, sensor faulty, or the hoses from the sensor are collapsed.

It's going to need somebody who knows what they are doing with merc diag kit really!

 

[Ian bulley]

Ah ok it's had a brand new DPF fitted by merc so maybe they've damaged something?

 

[alexanderfoti]

Ah ok it's had a brand new DPF fitted by merc so maybe they've damaged something?

It's either leaking at the flanges or there is an issue with the sensor or the hoses!

 

[Ian bulley]

OK thanks ill take it to a different garage.

I think merc aren't interested if the star machine doesn't give them clear instructions to replace specific parts. It's not really old fashioned fault finding

 

[alexanderfoti]

Yes, although you should push them if they have changed the part and not fixed the problem.