I just bought a 2001 E55 AMG with 84K from a used car dealer. Almost immediately after I bought it a "check engine light" came on. I took it back to the dealer and he ran the code as a "fuel trim right bank" (or something like that...) and explained it was an oxygen sensor code.

OK, so we were going to address that issue the following Monday, but on Sunday, my wife drove it and it went into limp mode--second gear only. She pulled into a parking lot and put it in park and turned it off. She then turned it back on and it wouldn't come out of park.

I came to pick her up and manually got the car to go into drive. It was still in limp mode so I drove it home and arranged for a tow the next morning.

We flatbedded it to a small shop who ran the codes again and got a P0705, a transmission range sensor circuit error. He implied that the shifter mechanism would need to be replaced.

I am going to have the car re-towed to a Mercedes dealer where they can hook it up to a REAL diagnositic machine and let me know what's really going on. I find it hard to believe that the shifter mechanism is broken so shortly after receiving a CEL for an 02 sensor. I really think this problem is something simple.

Thoughts?

Easy- something got spilled in the shifter- easy to do, cup holder right there.. the shifter is a computer...so liquid, not so good...

BTW..PO173 is usually a MAF ....but COULD be an O2..

Thanks for the help. I know for a fact that nothing was spilled on the console during the time I've owned it.

Could the second code for the PRND switch be tripped by the problems from the first code, whether it is the 02 sensor or the MAF?

I guess I'm not sure what the root problem is, or how much this is all going to cost...

no, youve got 2 seperate things here..

I had the shifter break in my 00' 230K - nothing spilled in it.My gf took the car to the mall came out and couldn't put into reverse. I had to stick a screwdriver down inside it and hit the release mechanism and drive it to my mechanics shop , $130.00 later - fixed.

Different thing.....

I flatbedded the car to a Mercedes authorized repair center and they ran diagnostics on it.

He said there were a variety of codes popping up, but the main one was tripped by a sensor in the shifter, which sent an error message to the transmission, which relayed it to engine which put the car in limp mode, or something like that...

He cleared all the codes and inspected the shift module, which he said looked fine. They drove the car for a half hour and went through 2 cycles. No more lights came on.

He said it was possible that a brake sensor tripped the entire thing, but he didn't think anything was physically wrong with the car.

Are these cars THAT sensitive to error codes that it would shut down the main drive systems when there is (apparently) nothing mechanically wrong with the car?

Don't know if this helps, but this stuck in park fault is usually the stop light switch, which has 2 sets of contacts in it. One set for the stop lamps and one set for the ecu. If this fails it will trigger a fault code in the ecu.