oxygen sensor harness routing .. where does it go ??
Hello, I just got a 98 318ti .. neat car ... Downside is the check engine light was on . I replaced the rear 02 sensor and the light didnt go away . I was getting codes that said the o2 heater was not working ... po136 p1186 p0420 checked the wire that power the heater on the harness and no voltage .. (should be 12v)
I put my scan tool on it and the 02 voltage was betewwn .4 and .43 v .. lots of spikes , not flowing as a normal downstream 02 sensor . I then disconnected the sensor from the harness and the spikes stayed the same , so it is obvious the sensor is not being read . Not sure what is making the spikes ..
Where does the post 02 sensor rouit to ?? Looks like it goes up the firewall under the wipers .
I am thinking the conection on the other end is dirty or possible a busted wire some where . Under the car I took off the sheetmetal cover that goes over the fuel filter and saw no damage to the wires in that area ..
Any suggestions ?