I recently had some work done on my '98 jeep cherokee classic (4.0 I6)-4wd

Ignition coil, rotor, wires, plugs...and now the CEL came on and I get the code P0138. This is my downstream O2 sensor, correct?

My other question is this: Could the above ignition work have an impact on the new CEL problem. The place I took it has a fixed forever warranty and I would like to take it back to them if this is the case. Free is always better.

Your help is appreciated!

-K

 

No, I don't see a connection in work performed and your code.

Yes, the code is referring to your downstream (after-cat) oxygen sensor.

First inspect the wiring/connector.

Know that the oxygen sensor has a finite lifespan of between 100k to 150k so if you are at or over this mileage, replacing your oxygen sensors wouldn't be wrong. If you are doing one, I'd do them both as the other (upstream) is not far behind and the upstream one is the one that contributes to your fuel / air mixture ( = gas mileage).

And if you do replace any oxygen sensor, shop for a name brand like Bosch or NTK. Stay away from the el-cheapo no name crap floating around on e-bay. It is junk.