97 318ti p0135 and p0136 OBD codes?
 

I have a 97 BMW318ti that has been flashing OBD codes OBD II P0135 Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) and Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2). I replaced both the front and rear O2 sensors with plug in style (not splice). If I reset the code, the light will come back on with the exact same codes after 10 or 15 minutes of driving. I checked the O2 heater relay and it appears to test out ok, but it is not the k6309 relay that all of the part sites says it calls for. I believe it is a k6303.

Anyone have any idea what the deal may be? I've searched for hours online and haven't found any postings about tgus code combination.

Thanks.

The O2 heater circuit is not getting power so I would start by changing the relay. I checked the Bentley and can't find a fuse but there has to be one so ensure you check all fuses with a OHM meter. Also look for broken or damaged wires.

This will most likely be a nightmare to find the issue. I pinched a O2 wire when I installed a clutch and it caused this code and took forever to find.

Best, John S