I have a 98 honda civic lx. My check engine light is on so i got a diagnostic reading and it says p0135 and p0141 are no good so I bought the lower sensor not the primary sensor cause the lower sensor was missing when the mechanic lifted my car up and where the sensor insert hole was there was only a bolt the same type used for the oil tank that was inserted there to cap the hole up and I thought that could of have been the source of the problem so i bought the lower sensor but still check engine light stays on when he put the new sensor .

So i got another diagnostic reading and instead of getting the codes the mechanic checked to see what is on or off while the car was on and it says that my o2 sensors are both off. I bought this car not too long ago and the person who had this car before me did some modification to it he took off the bulb for the check engine light so that he can sell the car without any hassels. He cut one of the wire harness sensors where the lower sensor was missing and put a male plug-in end of the wire harness (when the end of the wire harness is suppose to be a female plug-in port)for the lower o2 sensor not the primary sensor without connecting a o2 sensor to it. And I really dont/cant understand why he did this.

So if you can help me before I bring my car to an electrian and spend big bucks please let me know and I will be so greatful.

Oh yeah I followed where the wires goes for the o2 sensors with my hands and eyes and they lead me to the back of the engine and i saw a cut wire (all black with a yellow stripe) could this be the problem cause the mechanic says he doesnt see any other cut wire that might connect to it so please please please help me... Thanks you so much for taking the time to read this...