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P0136 Fault Reappears in 2003 Toyota Highlander AWD - Sensor Replacement Issue

Model: 2003 Highlander Fault Code: P0136 Posted: 2012-11-08 15:23

I own a 2003 Toyota Highlander with a 6-cylinder AWD system. Approximately 11,000 miles ago, I received a P0136 diagnostic trouble code. I replaced both the upstream and downstream oxygen sensors as recommended. However, the P0136 code has returned, now showing variations such as 01/02 and 02/02 P. I used Bosch O2 sensors with OEM-style connectors (not universal), and the issue persists. I am due for a state inspection, which will fail without resolving this code. Any insights or troubleshooting steps would be greatly appreciated.

Related fault codes
P0136
Comments (1)
Anonymous 2012-11-09 08:44

Check the wiring harness, connectors, and fuses supplying power and ground to the oxygen sensors. If all connections are intact, remove the current Bosch O2 sensors and replace them with factory-original sensors from a dealership. Aftermarket sensors often fail to meet the PCM's mapping requirements and may trigger persistent P0136 codes.