P0135 and P2251 Codes - 2012 Tucson Limited 2.4l
 

Hello,

I have a issue with my 2012 Tucson Limited 2.4l.

The issue are the two (P0135 and P2251) codes can't be permanently cleared.

I had some recent exhaust work done after an attempted theft of the Cat. The front flex pipe with
the upstream 02 sensor and the trailing resonator pipe were partially cut and welded for a repair.

After this work, the codes appeared. Based on this the upstream sensor was replaced. Unfortunately, this did not permanently remove the two codes after the repair work and sensor replacement.

If I clear the codes upon vehicle startup, they will not return during that driving cycle. Upon next startup, they will reappear (either leaving sitting there for a couple of minutes or just starting to drive). This cycle can be repeated continuously.

This seems rather odd to me.

Does anyone have any thoughts?

Thanks, Scott

There is a good possibility either in the process of attempted converter theft or attempted repairs that some wiring might have been damaged.
A thorough check of the oxygen heater circuit and integrity of the wiring bringing power to the sensor or signal from the sensor to the computer should be done.

Thanks Hanky. I just don't understand why the errors are only thrown at startup vs again during the operation of the vehicle. Is there some test only being done at startup but not during operation? Does the no error generation during operation mean this is a benign issue? Thx Scott

You are on the right path. Many systems on vehicles today do run a pre-check to insure the system is complete.
If there is any open circuit for instance, the pre-check will notify the operator something is wrong. Usually a pre check failure is pretty easy to pin down because the vehicle doesn't have to move or be moving to show up. Again a code will usually tell which system has the problem and the testing starts there.

Hello Hanky, Thx for the feedback... I have somewhere to go now... Thx Scott

Hope everyone had a Happy Thanksgiving.