My car has 57,500 miles on it. Code p0136 – O2 Sensor Ban1 Sensor 2 – came on. So I bought a new one at the auto parts store and put it in. I reset the code and drove for about 25 miles. But then I got a P0141 - same unit heater malfunction. I told the supplier and got a free replacement. I put it in the free replacement, cleared the code and about 20 minutes later after driving the code came up again. Do you have any suggestions?
Although these codes are both for the downstream O2 sensor, they are completely different. The first code, P0136, has to do with actual sensor performance. The second code, P0141, has to do with the sensor heater circuit performance.
The hybrid vehicle control ECU will turn on the heater for a brief period during a cold start to bring the sensor up to operating temperature. The O2 sensor itself sends a signal back to the hybrid vehicle control ECU to keep it apprised of catalytic converter performance.
In other words, these codes are for two separate circuits. The only thing these two codes have in common is are the ECU and the O2 sensor itself.
Since you've already replaced the sensor, all signs point towards the ECU. The good news is, the ECU probably does not need to be replaced. There is a technical service bulletin (TSB) for updating the module when code P0136 is set. The number TSB number is L-TCI-3140.
A trained professional, like one from YourMechanic, will have an OEM scanner and can diagnose these codes and perform the appropriate repairs for you.
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