What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P0139HO2S CIRCUIT MALFUNCTIONManufacturer communications
1Original wording in English
MAZDA
Reported code forms P0139
SOME VEHICLES MAY EXPERIENCE THE MIL ON WITH DTC P0139 (HO2S CIRCUIT MALFUNCTION) STORED IN PCM MEMORY. THE PCM:1.MONITORS FOR A TIME-OUT MALFUNCTION (WHEN HO2S REMAINS ABOVE 0.2V FOR LONGER THAN A SPECIFIED PERIOD OF…
Check vehicle applicability
1A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Mazda | MAZDA5 | 2010 |
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.