So my 98 civic has the P0135 code. Yesterday my friend gave me an old o2 sensor that is supposed to work fine. I did the swap and cleared computer with my scan tool. 2 seconds after I turned on the car again the same code turned on. is it againa bad o2 sensor or wiring issue. the reason why the 1st o2 sensor came on is because the guy that swaped the engine did not screw on the rubber feet on the bottom of the ac fan, so the only thing holding it on was the top mount. so the whole assembly eventually slipped and since the fan was on it eventually damaged the sensor. I dont want to buy a new one and still not fix the problem, but I do need to fix it since the inspection will be expired at the end of this month. can anyone help?

 

Did you replace the right sensor? Code 135 comes from the heater circuit of the first one. Check your "new" sensor by measuring resistance between the two wires that are the same color, it should be < 50 ohms. If open circuit, sensor is bad. If the heater checks OK see if the car is supplying 12 volts to those wires. That would be the fuse 15 problem though you usually get codes for both sensors (P0135 and P0139) when that happens. If the fan damaged the wires that could have blown the fuse.

 

Well since I dont really know how to use a voltimeter I swapped the 2 sensors, so after that I reset computer. Now it only gives the p0141 vs the p0135. So I guess the o2 is bad after all.