Oxygen sensor replacement for 1997 Pontiac Grand Am (GM 2.4L)

    The check engine light (it’s an icon of an engine) came on, first intermittently, and then all the time. I used an Innova OBD2 code reader to find out which code was set. The reader pointed to the rear oxygen sensor, mounted in the exhaust pipe, downstream from the catalytic converter. Although the car will run with a bad sensor, it should be promptly replaced because the fuel delivery system will run in “open loop”, wasting gas.
   This is a simple repair. Very few tools are required. The prime difficulty is in removing the sensor from the pipe. It will have become quite attached to the pipe and will need some persuasion to come out.
The way these are manufactured makes it impossible to use a simple socket to turn it off. There is a special tool, basically a cut out socket with an offset square opening for a breaker bar. This tool must be purchased, rented or borrowed. I use Advance Auto and their handy tool-lending program to do the job.
   Drive the car onto ramps to improve under vehicle access. Slide under from the passenger side about midway on the vehicle. The sensor will be sticking out of a section of exhaust pipe after the catalytic converter.
   Disconnect the battery. The OEM wiring harness on this vehicle goes all the way into the main electronic unit under the hood. Unless using a rather expensive OEM harness, the original sensor wiring will have to be cut off and an aftermarket universal replacement sensor spliced into the original harness. The universal is half the cost of the OEM and it works great.

The sensor is just downstream from the catalyst

 
   
                                               With the wires cut off the sensor, try to get it out of the pipe. Go ahead and try, with the exhaust pipe warmed up. It never hurts to try, but I recommend heating all around the bung (the fitting that the sensor mounts in) with a propane torch. Put on some heavy work gloves, this is going to get hot. Torch all around it until the bung gets cherry red. It will take a good five minutes. Now it should turn off with the special socket tool.

  I use Bosch oxygen sensors. They splice into the original OEM wiring with a kit of connectors and insulators and seals. The kit contains very good and detailed instructions. It takes a little time and attention to detail, but the savings over a new OEM wiring harness are substantial. Bye, bye, check engine light.

    This is a direct fit sensor               Great reader                     removal tool