Hi I had posted previously about my 2011 CLS 350 (218) which had an odd limp mode (no dash lights) and came up with a Y77/1 Boost pressure positioner is faulty error code. My local indy said I needed a new turbo based on this, however after some advice on here I pursued replacing the turbo actuator - which I have just completed this morning (I bought a reconditioned one from turbo vanes) - I also replaced the seal on the main turbo inlet as it was worn, and the one on that breather to the left side of the batwing assembly. All went well... however after a 25 mile test drive and some kicking down to check the turbo was working ok, the car went into limp again, no dash lights. The error code above shows on my cheapo OBD scanner - 'The positive control deviation during boost pressure control is too high'. When I restart the car or clear the code it worked fine - but did the same on another test drive. Any ideas on what this could be? Thanks Phil
'Positive control deviation during boost pressure control is too high' 123900 M642 engine
- Thread starter Philo999
- Start date
Page may contain affiliate links. Please see terms for details.
Thanks. I put in a new O ring to the output pipe from the turbo and sprayed a can of turbo cleaner into the intake so I'm hoping that may help too. Went ok on a gentle test drive after the turbo cleaner as recommended by Wynn's - need to take it for a proper run and kick it down again and see if the error code comes up again.
Still have that error code and limp on kicking down. Turbovanes suggested seeing if the vanes were clogged with carbon - I don't think so and used a can of cleaner as mentioned before. They also then suggested a smke test to check for air leaks - don't know about this - any suggestions anyone? Thanks Phil
W1ghty
MB Enthusiast
Any update buddy ?
Spyros777
Active Member
i am facing a similar issue here, STAR reads low and high boost pressures car goes into limp mode. Please let us have an update if the problem has resolved and how. Thank you.
