Service Engine Soon
Using your car's on board diagnostic system


P0138, P0139, P0140 codes on a 2000 Nissan Maxima

Often, when driving longer distances in bumper to bumper traffic, the MIL would go on and some combination of codes P0138 "O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)", P0139 "O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)", and P0140 "O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)" would occur. I cleared the light, but the problem persisted over more than a year. I worked with the service manager at the dealer and finally solved the problem. Based on the information I gave him, he investigated the problem in detail. He determined that my car was equipped with the California emissions package. Because I bought the car in New Jersey where I live, this was unexpected. He also determined that there is a known bug in the on board computer specific to the California emissions package. The computer is covered under warranty for 80,000 miles. Because the computer was the root cause of the oxygen sensor problems they were replaced at no charge. The computer bug was also fixed.

This illustrates the value of keeping a detailed log of the scan codes and discussing this information carefully with a knowledgeable and helpful service manager. 

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service engine soon, mic light, auto repair, obd II, on board diagnostics,code reader 2005 Leland R. Beaumont