limp home mode/asr light on - HELP!
 

I have a sporadic problem with my 94 600sel. Sometimes the ASR light comes on and power is cut so the car seems to be running only on 6 cylinders, if I stop the car and turn off the ignition, on turning on the ignition again the problem is gone and everything seems to work OK. Problem happens at both low and high speeds and with the cruise control both on or off and seems to be occurring more frequently now (on average 3-4 times per 500 miles) does anyone know what the problem may be and how to fix?
TIA.

Limp Home Mode Reply
 

Most Likely Its The "throttle Body" Gone Bad. Could Be Other Things But Only Way To Tell Is Go To Dealer And Have Them Read Codes From Computer. Plan To Have Lots Of Money For The Repair.

That Part Is $750-900 Plus Lots Of Labor And Technical Knowledge.

I have seen many things set this off. The simplest were throttle linkage adjustments, but the fact it happens at speed probably eliminates that. Another common problem is the switch in the gas pedal (if it has one.. I always have to check the wiring diagram to be sure). I have also seen the alternator cause it and of course that car fits into the years where wiring harnesses deteriation could duplicate the problems of the systems they connect.

And then as stated above the throttle assemblies (2 on a 600) are the major cause.

Also try cleaning the wheel speed sensors in each front wheel. And make sure the throttle linkage is clean and lubricated and has a little play. Bad throttle body has to be the most misdiagnosed, overdiagosed problem ever. In my last five cars I've gotten at least 10 diagnoses, amateur and professional, of a bad throttle body and never once has that actually been the problem. It's a very fashionable diagnosis but you should exhaust all other possibilities first. An awful lot of throttle bodies get replaced at great cost only to have the problem persist.

Two other easy checks that can cause the problem are a bunched up floor mat/rug at pedal and unequal tire pressure/size...