Sensors P1281 and P0138 Diagnostic problem

[Pelochin1]

Hello Jeepers,

I have a Jeep wrangler TJ 2001 4.0L Automatic. Has anybody had a check engine light on with the P0138 and P1281 codes? what do you guys recommend me to do to fix this issue.

Thank you

 

[Daryl]

Remove your thermostat and test or replace it for the P1281. Clear the codes and see if the P0138 comes back.

 

[Pelochin1]

Remove your thermostat and test or replace it for the P1281. Clear the codes and see if the P0138 comes back.

Thank you Daryl, will do

 

[CharlesHS]

The two codes are probably related. Engine not warming up to more than 180* and high voltage on the O2 sensor means the engine is running rich due to not coming out of warm up cycle. This can be caused by a bad thermostat, coolant temperature sensor not reading properly or even low coolant.