P2A07
O2 Sensor Negative Voltage Bank 1 Sensor 2
Fuel & air metering (emissions)
Generic OBD-II
Low
What it means
P2A07 means the downstream oxygen sensor on bank 1 (sensor 2, after the catalytic converter) reported an implausible negative voltage. This sensor is used chiefly to monitor the catalytic converter, so the engine usually runs normally and the main impact is a check-engine light and a failed emissions monitor. Typical causes are a bad sensor, a shorted or grounded wire, or a corroded connector.
Low
Can I keep driving? Yes — the car generally drives normally; this downstream sensor mainly affects emissions monitoring, not how the engine runs.
Common symptoms
What you'll notice
- Check-engine light on
- Often no noticeable driveability change
- Possible slightly higher fuel consumption
- Failed emissions/readiness monitor for the catalytic converter
Common causes
Most likely first
- Faulty downstream (post-cat) O2 sensor, bank 1 sensor 2Likely
- Wiring shorted or grounded, driving the signal negativeCommon
- Corroded or loose O2-sensor connectorCommon
- Exhaust leak near the sensor skewing readingsLess often
- Faulty PCM ground or input circuit (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame and confirm the code is on the downstream (sensor 2) circuit.
- Inspect the bank 1 sensor 2 connector and wiring for shorts, grounding, or corrosion.
- Check for exhaust leaks upstream of the sensor.
- Compare the sensor's live data to a known-good pattern; replace the sensor if it reads negative/out of range.
- Clear the code and re-run the drive cycle to confirm the monitor passes.
FAQ
Quick answers
Is it safe to drive with P2A07?+
Yes. This downstream oxygen sensor is used mainly to monitor the catalytic converter, so the engine usually runs fine. Fix it to pass emissions and clear the light.
Can I just clear P2A07?+
It returns if the sensor or wiring is at fault. Repair the circuit or replace the sensor so the emissions monitor can complete.
Related codes
Often seen with P2A07
Read & clear P2A07 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX