W204 C250 CDi fault codes?

[Red302]

Hi all,

I've got a 2013 W204 C250 Cdi with the AMG pack. I've had it around 4 months and it is just shy of 120000 miles on the clock.

The car wasn't driven during the last week of cold weather, but now the EML has come on, and at idle, there is a slightly noticeable "shake" which I assume is a bit of a misfire. other than a slight drop in performance and change of engine tone, it seems fine. My blowers are also a bit intermittent, but less of an issue.

A friend has an OBD scanner, so we plugged it in today and got the following outputs:

P008791 - Fuel pressure too low
P047128 - Exhaust back pressure sensor 1 has a malfunction
P008922 - Fuel pressure regulating valve 1 has a malfunction, signal amplitude is greater than maximum.

The Control Unit Fuel Pump shows as OK.
These show as STORED as the EML has gone off, but the engine "sway" is still noticeable.

Does anyone have any ideas on what the fault could be?

It also showed the following faults that I assume are unrelated, but I haven't recognised any other faults, and I'm not sure what these refer to:

B179715 - Left standing light 2 has a malfunction. there is a short circuit to positive or an open circuit
B179B15 - Right standing light 2 has a malfunction. there is a short circuit to positive or an open circuit


Can anyone shed any light?

Thanks in advance!

 

[Gazwould]

Sometimes it's the battery has got weak/ dying and all sorts come up .

 

[Corty]

The fuel pressure regulating valve could be causing the low fuel pressure, though its possible that the fuel rail pressure sensor could be reading correctly there. The 0471 is a sensor that's fitted to the egr at the rear of it. I had this code and replaced the back pressure valve and that did seem to smooth my engine out ( though can't 100% say if it was a real change or my imagination looking for an improvement to justify the repair).Also my car kept coming up with the dpf pressure sensor being faulty and and code 2453 iirc, after a few wasted attempts at changing it my local indie said its the fuel rail pressure sensor, so had that done and its running smooth now and no false dpf codes. Incidentally both codes put the car into limp mode but no eml. I don't know if any of this may help you or just make it more confusing .

 

[Red302]

The fuel pressure regulating valve could be causing the low fuel pressure, though its possible that the fuel rail pressure sensor could be reading correctly there. The 0471 is a sensor that's fitted to the egr at the rear of it. I had this code and replaced the back pressure valve and that did seem to smooth my engine out ( though can't 100% say if it was a real change or my imagination looking for an improvement to justify the repair).Also my car kept coming up with the dpf pressure sensor being faulty and and code 2453 iirc, after a few wasted attempts at changing it my local indie said its the fuel rail pressure sensor, so had that done and its running smooth now and no false dpf codes. Incidentally both codes put the car into limp mode but no eml. I don't know if any of this may help you or just make it more confusing .

Hi,
Thanks for the reply!
I've still not sorted it - I changed the Exhaust back pressure sensor and changed the fuel filter in case that was the fuel pressure issue, but with no luck.
I took it to a local indy who reset the diagnostics, which then returned no faults and the engine was running perfectly. 1 week later and it was back to running rough and the EML light was on - but not every time. Took it back, and he said there was no faults showing, but that fuel pressure fault had flashed up briefly, but it's still running rough. Thankfully he didn't charge me either time.
Most times the EML is off on start up, but comes on under a bit of acceleration, motorway on ramp etc. It's passed an MOT so it can't be affecting the emissions too much.
I plan on taking it to a different indy, hopefully they'll have a better idea!