Codes P0138 and P0136?

NEIL2002CIVIC

MEMBER
2009 TOYOTA COROLLA
1.8L
4 CYL
2WD
AUTOMATIC
123,000 MILES

Hi, I have the car listed above with a check engine light. I've cleared the codes, and both came back pending and permanent. It runs fine otherwise.
I suspect a bad sensor (car sat for a year).
I'm going under the car to do a visual of the wires and connector. No vacuum leaks and intake hose looks good. No hissing/whistling or high idle.

Can I please have the test procedure with voltage output at the connector for the 02 sensor before condemning the part? A picture would help greatly. Any help is appreciated. I hope I'm going in the right direction. Thanks.
Have a great day,
Neil

1 Reply

LUCASNIC

MECHANIC
9 POSTS

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.

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