Posted on the x204 group and it never made it past the moderator, this is probably a better choice.

Had a front driveshaft failure at speed and it caused other damage, as tends to happen. It hit the transmission hard enough to create a hairline crack and it took out the right side upstream O2 sensor and put a couple of dents in the catalytic convertor. Took it to non-Mercedes shop who were able to replace the driveshaft and the sensor. When they returned the car it was running again but still had the P0135 code for heater circuit on the upstream O2 sensor plus P0301, P0302, P0303 misfire codes as a result of the sensor apparently not working correctly.

I patched the hairline crack in the transmission with JB-Weld, and it seems to be working just fine, dropped the transmission pan, replaced the filter, filled the transmission to spec. Transmission is fine. Also replaced the right catalytic converter since it had some "deepish" dents.



Have spent a couple of weekends trying to diagnose the sensor issue. Swapped the sensor again just in case, nothing. Swapped sensors side to side and the issue stays on the right side.



Bottom line is if you reset the codes, the car drives perfectly for 10-15 minutes or 3-5 miles and the codes come back. Once the code comes back it starts running rough again. I checked the plug that comes down from the car's computer and there is indeed voltage across the heater circuit (Middle two pins) and there is plausible voltage on other pins. As far as I can tell there is no fuse inline to the sensor- plus if it was blown there would be no voltage across the heater pins anyway, right?



So hoping the fellow forum members can point me in the right direction.



Thanks,

Joe L.