For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio.
Honda: 07-019: Mil Comes On With DTC P0139: Honda: 07-021: Moan Or Groan From Rear Differential In Cold Weather: Honda: 07-022: No Back-Up Circuit For Trailer In Vehicle's Rear Wire Harness: Honda: 07-023: Driver's Power Seat Doesn't Move Forward Or Backward: Honda: 07-024: Moan Or Groan From The Rear Differential: Honda: 07-025: Power Windows.I speak this because I had a pesky p0139 secondary o2 slow response and it didn't fix with an oem/Bosch/or rock auto sensor. DTC Troubleshooting: P0139 (65-3) How to Troubleshoot Fuel and Emissions Systems DTC Troubleshooting: P0607 (0-29) DTC Troubleshooting: P0511 (14-12) DTC Troubleshooting: P0563 (34-2) DTC Troubleshooting: P2647 (22-2) Wiring Diagram Front Fog Lights Adjustment Symptom Troubleshooting: No picture is shown on the display Rear Air Outlet Replacement.
The cat would be the most expensive so I would look at the wiring and sensor itself first.
OBD II Code P0139 So it looks like either the sensor after the catalytic converter is bad, wiring is bad or the cat itself may be bad.
