I have a 97 honda civic EX, i replaced the O2 sensor before the cat with a universal O2 Sensor and the CEL went off for a few days then poped back on. When i went to go get it checked; it was the same code p0135. I have black soot on my bumper and im wondering if one or more of my injectors are shooting to much fuel and blowing my Sensor off. I have heard a cold air intake system can do something towards running your engine rich but that doesnt really make any sense to me. should i replace the o2 sensor with an OEM part? Or pull off my injectors?

 

If fuse 15 is not blown, then triple check your wiring job. Did you solder your wire splices?

 

Code 135 is the heater circuit, going to be a problem with the sensor, wiring, or fuse. Wrong A/F ratio due to bad injector will cause a different code.