Grey350

Hello

My 2008 CLS350 (June 08 build with 'VGS2' conductor plate) occasionally goes into limp mode but once the engine is turned off and restarted the transmission operates normally as if nothing had happened.
A recent trans. service with correct fluid and filter by a reputable M.B independent shop has made no difference and it always happens when I accelerate from standstill, eg., moving off gently from traffic lights.
What is confusing is that no fault codes are being recorded after hooking up a scanner. I have done this with my own 'icarsoft MB11' scanner and two separate M.B independent shops have done the same however in neither of the individual tests were any codes recorded.
Any advice as to what I should do to address the underlying fault/cause would be appreciated. I assume there is a problem but without a code I don't know where to start.
The car is in very nice, almost 'As new' condition with only 114,000kms; one previous owner with all service records since new - M.B dealer and M.B independent.

Thank you in advance

chassis

Speed sensor, solenoid valve, and harness connector failures come up from time to time on the 7G. Do a search on this site.

Limp mode is electronically induced. I would look for a problem related to electronics. If there are no fault codes, the computer thinks there is no problem. To me this means that the computer's eyes and ears (sensors) are the problem.

Replacing the conductor plate without first confirming it is needed could be expensive. It's where I would focus my efforts, to determine what has failed and what needs to be replaced.

Please provide more detailed and comprehensive diagnostic information.

Grey350

Thank you for you reply 'Chassis'. Could I please clarify two points so that I can navigate through this issue which is puzzling due to the absence of fault codes.

1/ When you refer to the computer (see 'thinks there is a problem') are you referring to the Siemens/VDO TCU fitted on/to the conductor plate?
If so, I assume that would mean if it was defective then it would have to be replaced (by M.B dealer) with the complete conductor plate, ie., as a whole unit?

2/ I have done some previous research which mentioned the three items you refer to having also seen passing reference to ABS sensor, brake light switch and steering angle sensor. If any of those items were the cause of the car occasionally going into 'Limp' mode should relevant fault codes be picked up by a 'icarsoft MB11' scanner?

Thank you again.


,

chassis

@Grey350

1. Yes, the computer in the transmission. I have not replaced this, it has been written about on this site several times. Do you DIY or will a shop do this, if you determine it's needed on your transmission?

2. I don't know, I haven't had to diagnose codes (yet).

Grey350

Thank you. As the problem only occurs about every sixth time I drive the car (driven once weekly;100km +) I'll just monitor it and if/when it gets worse take it to the M.B dealer whereby I'll eventually advise the final outcome.

Regards,
J