P0025 Intermittent
 

Re: 2010 GL450 4.6 V8 155k miles (new to me 6mo)

Hello All - After the first trigger of the CEL with a P0025 code, I did the simplest and cheapest thing (after trying a rest of course) I replaced the CamPS, this did not solve the issue. I reset CEL it stayed off for a day or so, but came back, also over time with it came occasional rough idle and some slight stumbling which of course would have led me to that the VVT is actually not working vs a sensor verifying.

Next step seems to be the exhaust VVT control assembly, which I see MB sells in 2 parts, the actuator and the mechanical valve. Any advice as to which is the typical one to fail? I would just replace both, both the mechanical assembly is $130-$150 so in a situation where I am kinda of throwing parts at it not knowing whether it is that the actuator isn't moving the valve like it is supposed to or the valve is not moving like the actuator is asking it to... magnet weak or the valve have resistant that the magnet can't overcome etc.

** The oil was recently change and I used the factory recommended oil/viscosity, though the problem did start after my first oil change (purchased used).