Good morning,
I own a 2006 Honda Accord 4 cylinder with 150k miles. About 8 months ago my check engine light came on and the diagnostic code read P0139. I replaced the downstream (sensor 2) O2 sensor with an after market Bosch part. I erased the PCM code and it was fine for approximately 3 months. After that the code came back. I took the car to the Honda dealer, they ran diagnostics and updated my PCM software and told me if it came back then to replace the sensor with a Honda OEM O2 Sensor. About 2 months later it came back, I just erased the code as the vehicle ran fine. It did come on one more time, and again, I just erased the code. Yesterday, the check engine light came on but this time the code was P0134. Should I replace sensor 2 O2 sensor and sensor 1 O2 with factory OEM parts? I checked the O2 heater fuses and them all were fine? Any suggestions? Thank you for your help.

Chris

 

For Hondas as well as many other makes of cars, Bosch O2 sensors are absolute crap. I would change both your upstream and downstream sensors with either sensors from Honda or Denso (the OEM maker).

 

Thank you, I will give that a shot.

Chris

 

What was the resolution? I have a 2005 Accord LX 2.4 non-CA. I also have P0139. Changed injectors, OEM oxygen sensor 2, gas cap, air filter, cleaned MAF, CEL still comes back after a few miles of reset. Runs fine but will not pass emissions. Perplexed.