Oxygen sensor replacement for 1998 Dodge Caravan

  The check engine light (or an icon of an engine) came on, first intermittently, and then all the time. I used an 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 van 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.
   First unplug the sensor from the vehicle. Follow the sensor wiring to a 4-inch diameter rubber grommet near the sensor. Pry the grommet out and unplug the sensor.

Under body view of rear Oxygen sensor, grommet and connector

   
  With the sensor unplugged, try to get it out of the pipe. 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. Fire it up and enjoy the absence of that bothersome "check engine" light.

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