What it means
The oxygen sensor signal circuit is shorted to its heater circuit on Bank 1 Sensor 1. This electrical fault can make the sensor reading unreliable.
How it works
The Bank 1 Sensor 1 oxygen sensor is upstream of the catalytic converter and reports oxygen in the exhaust so the controller can adjust the air-fuel mixture. P2231 sets when its signal circuit is electrically shorted to its heater circuit, which can corrupt the upstream reading and interfere with mixture control.
Common causes
Most likely first.
- Damaged oxygen sensor wiring
- Shorted oxygen sensor internally
- Melted or chafed harness near exhaust
- Corroded or damaged connector
- Control module fault
Symptoms
- Check engine light
- Poor fuel economy
- Rough running
- Increased emissions
How to diagnose it
- Record freeze-frame data and check live Bank 1 Sensor 1 data and fuel trims to see whether the upstream signal is implausible or mixture control is affected.
- With the exhaust cool, inspect the Bank 1 Sensor 1 wiring and connector for melted insulation, chafing, contamination, corrosion, or damage near the exhaust.
- Use the vehicle wiring diagram to identify the signal and heater circuits, then check for an unintended electrical connection between them.
- Inspect connector terminals and test the sensor-side circuits to distinguish a harness short from an internal sensor fault.
- If the wiring and sensor check out, follow the manufacturer's diagnostic procedure to assess the control-module circuit.
Common fixes
- Repair chafed or melted Bank 1 Sensor 1 wiring and restore proper routing.
- Clean or repair damaged or contaminated connector terminals.
- Replace the Bank 1 Sensor 1 oxygen sensor if its internal circuits are shorted.
- Repair the control-module circuit only if testing confirms a module-side fault.
Can I keep driving?
You can usually drive a short distance if the engine runs steadily, but avoid extended trips and heavy acceleration because faulty upstream feedback can worsen fuel economy, emissions, and engine running. Stop if the engine misfires badly or loses substantial power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.