P0131 code meaning
O2 Sensor Circuit Low Voltage Bank 1 Sensor 1
Powertrain system Generic code P01xx codes Check engine light
What P0131 means
The oxygen sensor before the catalytic converter on bank 1 (sensor 1) is the main control sensor for the mixture. It is either a switching sensor (about 0.1 V lean to 0.9 V rich) or a wide-band sensor that works with a pump current evaluated by an interface chip. On switching sensors it means the signal stays below about 40–60 mV (GM, two trips; some GM engines also require the downstream sensor to read rich at the same time, since a genuinely lean mixture would show there too). On wide-band sensors (Ford from 2011, GM) it has nothing to do with the mixture: the interface chip reports one of the sensor wires shorted to ground. A really lean mixture leads to P0171/P2195 rather than this code. A stored code usually switches mixture control to open loop and suspends adaptation and converter monitoring.
P0131 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P0131
- Check engine light on
- Higher consumption, possibly rough running (no mixture control)
- Higher emissions, possible emissions test failure
- Possibly with P0171/P2195
Common causes of P0131
- Most likelySignal wire (or a wide-band sensor wire) shorted to ground, e.g. chafed on exhaust or gearbox
- Most likelySensor faulty or poisoned (permanently lean signal)
- PossibleLarge exhaust leak ahead of the sensor or misfires
- PossibleConnector wet or corroded
- Less likelyControl module or interface chip faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor bank1 sensor1Oxygen sensor wiringEngine control module
What each part of P0131 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 31 | The exact fault in that area. |
What to do next
- Note P0131 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0131
What does P0131 mean?
P0131 means "O2 Sensor Circuit Low Voltage Bank 1 Sensor 1". The oxygen sensor before the catalytic converter on bank 1 (sensor 1) is the main control sensor for the mixture. It is a generic code, so it means the same on every make.
Is it safe to drive with P0131?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0131 fail an emissions test?
Yes, it can. P0131 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0131 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0131 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.