I just bought an out of state 1997 E420 sport (sight unseen) and after it rolled off the truck, I noticed the CE light was on (the seller of course failed to mention that small detail.) I read the codes with my BR3 OBD2 interface and came up with P0130, P0136, P0150, P0156 - all four oxygen sensors. Reset and drove. 2nd driving cycle CE back on. Took to shop I have worked with before, same codes. On the lift it is obvious the lower two oxygen sensors are new, upper two are not. (one of lower two appears to be the wrong sensor as the wire is too long, but tech says they all work the same - no problem.)

Tech replaces other two sensors and also notices the passenger cat appears to have been split open and re-welded (maybe nothing inside?) 2nd driving cycle CE back on. Back to tech who takes car to fellow tech with SDS machine. I get FOUR page printout of stuff, everything from 'alarm activated by brake pedal' to 'occasionally altitude correction' but nothing looks too serious. My tech isn't up on reading the printout (not his machine) but when I look at it, only five of the items are printed out as a black box with white writing (what does this mean?) they are P0130, P0136, P0150, P0156 (as before) and B1438 multi contour seat air demand too high (fixing the leaking hose to drivers seat this weekend). Tech tells me ME1 unit is toast and needs new one ($1600). Strangely, the car runs GREAT - strong acceleration, smooth idle, no problems. It does seem to be running a little rich, by smell, but not horribly so. Also mileage is not that great - maybe related?

Is there any way to further diagnose this problem? Can the ME1 be sent somewhere for repair? Could wiring external to the ME1 cause this? If I was able to find a used one, does it have to be recoded in order to work or is it 'plug and play'? Would a 1997 S420 ME1 work or is it specific to the W210.

As I just bought the car, I really do not want to throw almost 2 grand at it immediately - Especially for something that won't make it go faster or handle better. I would greatly appreciate some experienced assistance on this matter.