Mercedes7

Sorry if this is posted wrong only posted like once.
I've had these two errors which i think might be the same thing or at least closely related.
P25AA00 - The actuation for piston cooling has a short circuit to ground.

P25A900 - the actuation for piston cooling has an electrical fault or an open curcuit.

I have changed the part below since this is where the mechanic said the problem was but it didnt fix anything. I will attach images.







Changed it but still not fixed. Anyone ever had this problem or know what the fix might be?

The vehicle is a 2014 E250 cdi Bluetec 4Matic.

Quint22

Going to follow incase I run into the same problem on mine.

Curious was it a new part and if so did the codes get cleared after installing new part?

S-Prihadi

Ohh, so the diesel engine has its own oil valve to de-activate the piston cooling jet.
In gasoline M276, we only have the 2 stage pressure oil valve but at OIL PUMP, to do the same task and overall reduce oil pressure to save fuel.
You should test voltage/frequency/PWM sent by ECM to that oil valve to verify that wiring is good from ECM to the oil valve

See this for "example" : https://mbworld.org/forums/e-class-w...en-passed.html

CaliBenzDriver

• you got a code about "bad valve electrical..."
• you replaced the valve itself,
• the code remained!

Then what to do next???

Live tests:
-- A: ECU actuates one side of the solenoid: PWM?
-- B: The fixed side is a homerun to (GND/Fuse)

The easiest thing to do is work on testing B: the fixed side circuit:

1. What color is it ?
2. where does it go?
3. Does it hold under load or gets weak?

Then next is the ECU side:

• what does it bring
• are both supply and switch ok?

You almost have this all fixed up... don't give up in the last stretch.
🤞

Mercedes7

Update.

Got the car fixed last week,but have been too busy to post an update.

To answer Quint22, no the part was not new and the codes were cleared after the swap.

I went to the mercedes service shop after going to a few other shops before because where I live the mercedes service shop is known to not be able to fix things but just replacing parts. I asked them to check the wiring and they said there was nothing.


Last week i took the car to a service shop that a close friend recommended. When he checked the car with xentry he said that there could be a few causes for the problem, it could be wiring like S-Prihadi and CaliBenzDriver said or a problem on the ECU side like CaliBenzDriver mentioned.

After leaving the car for a day there turns out there was a problem with the wiring although i don't exactly know where. Went on a test drive with the mechanic and he drove the car pretty hard and no error or check engine light lit up.

I have been driving the car hard this week to test and make sure it is fixed and so far no problems but i do believe it is fixed.

Sorry for no replies for such a long time.

S-Prihadi

I hope the diesel engine oil cooling solenoid in discussion, is designed as a fail-safe version ( normally open ) like M276 2 stage oil pressure valve.
Meaning........... when the solenoid is defective or wiring bad or basically 2 stage oil valve does not work, the oil pressure is then normal higher oil pressure like how unregulated system is.