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Safe Mode?

JohnEclass

Active Member
Joined
Apr 26, 2012
Messages
453
Location
Planet Earth
Car
S6/Q5/C300/S4/W209/W211
So for probably the 3rd time in 18 months I set off and put my foot down exiting car park onto a clear road..... instead of accelerating off down the road the car coughed and shuddered as if I had hit the rev limiter ....which I hadn't
then would not accelerate apart from very slowly up to 2000 revs and would not go past this point?...:mad:
Tried in all modes C / S / M, nothing doing, by this point I was joining M56, all I could do was join and stay in lane 1 until the speed slowly crept up to 70, with coaxing up to 80 but stayed in lane 1 because if I had to brake for traffic it took an age to build up speed again.

As with the previous occasions the answer was .....turn it off and turn it back on again!!!:crazy: then all horses were restored and ready to be let loose.

had to go down to next junction come off and park up to switch off leave a few minutes then start up.

Any ideas?....is it a safe mode to stop you over revving a cold engine?

Is it dropping into limp home mode? :confused:

Any help appreciated :thumb:
 
Could be Turbo actuator, or sticking vanes
 
I had this once on my w208, it was the TPS (throttle position sensor). The sensor has two sets of resisters, each set to the opposite value. As long as the Engine ECU can see that the values are correct it knows your pressing the throttle. If one set of resisters changes value then the ECU knows there is a mismatch so your put into safe mode.

Get a quick check on STAR.

Just seen yours is limiting to 2000, mine revved higher, just very slowly so maybe be totally unrelated.
 
Last edited:
Had a similar issue with the wifes car, same engine as yours. Codes threw up an oxygen sensor. Replaced it and the car was fine until... 4 weeks later and it did it again only once though. It may be as merc85 says. The actuator on this car was a bit sticky and my indy loosened it off and greased it up. Looks like the problem may be back
Get to your garage and ask them to plug it in and start somewhere, it could be a dodgy sensor.
 
Thanks Star it is!
 

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