Skip the auto shop - Our mechanics make house calls

Q: P0139 HO2S-12 (Bank 1 Sensor 2) Circuit Slow Response - 2005 Honda Accord

asked by on

My car (Honda Accord EX Coupe L4 2005) had this code (P0139 HO2S-12 (Bank 1 Sensor 2) Circuit slow response) 2 month ago. But i didn't see any symptom; so i erased the code because i thought that should have been the sensor getting old. This morning the same code came up. My question is What is most probable in this case a bad sensor or a leaking in the fuel injector system?

My car has 101000 miles.
My car has an automatic transmission.

This code indicates that the rear oxygen sensor is not properly reading the oxygen content and adjusting the air/fuel ratio as it is supposed to. This can be caused the by the sensor not working properly, the wiring to the sensor being damaged or broken or potentially an exhaust leak. I would recommend checking the following to correct this:

  • Check and fix any exhaust leaks
  • Check for wiring problems (shorted, frayed wires)
  • Check the frequency and amplitude of the oxygen sensor (advanced)
  • Check for a deteriorating/contaminated oxygen sensor, replace if necessary
  • Check for inlet air leaks
  • Check the MAF sensor for proper operation

If you need some help with this, you may want to consider having an expert from YourMechanic come to your location to properly diagnose the trouble code and correct this problem.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. P0139 HO2S-12 (Bank 1 Sensor 2) Circuit Slow Response - 2005 Honda Accord

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Gasoline smell in car

You have to first exclude the possibility that the shop somehow spilled gasoline in the interior of the vehicle and/or sat in the car with gas on their clothes or placed any gas contaminated "stuff" (rags) in the vehicle or...

Q: Acceleration malfunction

If the car is missing an oxygen sensor, this needs to be addressed first. This can cause the computers to do all sorts of strange things. The PCM uses the O2 sensor to make most decisions for your car to...

Q: 05 Sable won't start. Turns over but won't fire. Fuel filter replaced, fuel pressure normal, car only starts with starting fluid.

Fuel pressure may be good but the injectors should be checked for operation. At cold start, there is a temperature sensor that must be working properly to signal the PCM to enrich the mixture on cold start. Are there any...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.