Codes p0138 and p0136?

These codes are associated with the oxygen sensor after the catalytic converter. (Bank 1 sensor 2). P0136 and P0138 are both circuit codes indicating a voltage out of a normal range for the sensor 2 oxygen sensor. Both of these codes could be caused by a shorted oxygen sensor or a circuit fault. You can check the resistance of the 4 circuits with the ECM and O2 sensor disconnected at the same time.

If there is a short in the circuits rather than the O2 sensor when you disconnect the ECM and check resistance between the two circuits, you will find low resistance. If the circuits are not shorted together, you will see OL or Out of Limits on the multimeter which is what you want. If there isn’t a shorted circuit, which is what we would be most concerned about considering the P0138, the most likely cause is the sensor itself. Attached are pictures of the connectors and the circuits for this oxygen sensor. You would check resistance between pins 1 and 2 and then between pins 3 and 4 and should get that OL reading. If you do, sensor replacement makes sense!

Let us know if you have additional questions.

Sorry for getting back so late. The problem was the 1st Sensor at the manifold giving poor signals to sensor 2. They were Tested when cold. That's when the problem existed... It was out of limits. It tested with in limits when hot. I replaced both sensors (Denso) Thanks for your help!

Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.