I need help at resolving this code. I have replaced the o2 sensors and have not been able to get rid of this CEL.

I had changed the o2 sensor on the passenger side manifold.

the reading said it was the heater circuit. Did this gen have a fuse for the heater element? I can't think of any other ways that this code would be generated besides the o2 has malfunctioned.

input please. TIA.

 

am I asking this question at the wrong place?

update on this: So I check around and made sure the hoses are connected properly and well secures. I removed the battery. I drove around and got the CEL again. Stopped to read the code and the code reader post nothing. Started the car and the CEL is gone... rode around again, CEL came on, got the reader plugged in and same result, no result. Started the car, CEL disappears again. Third time, I finally got the code, P0125. Cleared it and drove around again... this time, code p0125 and code p0135...cleared it and drove around... only code p0135 this time.

sux!

 

so I checked the radiator... it was full but not all the way topped out. I had to add...say three shot glasses worth of water to being close to overfill it.

The weird thing is, the coolant overflow is empty. ???

The guage is on the third line from the bottom when the engine reach operating temperature.

looks like the beginning of some bad things to come. My heater core could be leaking, may that explain the reservoir being empty? I checked the oil and it looked fine.

 

so this morning, I open the radiator cap and filled up the overflow. Started the car up and observed. Well, right away, the coolant starts to overflow... I immediately put the cap back on to prevent futher loss of the coolant.

What could it be? It doesn't over heat, could it be the thermostat? that doesn't explain why it's not overheating. Is it possible the water pump is done for? It could explain why the water is not circulating unless the cap is on and pressure is forcing it to circulate. I don't see any leak at the bottom.

again, the coolant temp is sitting just on the third line, below halfway mark and doesn't move much further that.

talkn to myself.

 

Take it to the shop let them do the pressure testing and check your cooling system properly. You may have a big air pocket inside the cooling system so the coolant temp. sensor can not pick up the air. They are designed to read water temp. not air.

 

thanks for the reply... im going to pressure test myself... i rented a block tester from autozone to make sure my head gasket is ok... i will pressure test this weekend.

so glad for tool rentals.