O2 Sensor Reference Voltage Circuit Low Bank 2 Sensor 1
Code P2249 indicates the oxygen sensor reference voltage circuit on Bank 2 is reading below the expected threshold. This prevents the PCM from accurately monitoring exhaust oxygen levels, affecting fuel trim and combustion efficiency.
What You Might Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Rough idle or hesitation during acceleration
- Stored lean or rich mixture codes
- Possible misfire conditions
Most Common Causes
- 1
Faulty oxygen sensor
The O2 sensor itself has failed or degraded, producing low or unstable voltage signals to the PCM.
- 2
Blown O2 sensor fuse or relay
A blown fuse or failed relay prevents proper power and ground supply to the oxygen sensor circuit.
- 3
Wiring or connector issues
Corroded, loose, or damaged wiring and connectors in the O2 sensor circuit reduce signal voltage.
- 4
PCM or ECU malfunction
A failing engine control module may misinterpret or fail to properly read the O2 sensor reference voltage.
How to Diagnose It
- 1
Check Faulty oxygen sensor — The O2 sensor itself has failed or degraded, producing low or unstable voltage signals to the PCM.
- 2
Check Blown O2 sensor fuse or relay — A blown fuse or failed relay prevents proper power and ground supply to the oxygen sensor circuit.
- 3
Check Wiring or connector issues — Corroded, loose, or damaged wiring and connectors in the O2 sensor circuit reduce signal voltage.
- 4
Check PCM or ECU malfunction — A failing engine control module may misinterpret or fail to properly read the O2 sensor reference voltage.
How to Fix It
- 1
Replace oxygen sensor Bank 2 Sensor 1
Remove and replace the faulty O2 sensor on Bank 2 with a new OEM or quality aftermarket unit. Ensure the sensor is torqued to specification and the connector is fully seated.
- 2
Inspect and repair wiring harness
Check the O2 sensor wiring for damage, corrosion, or loose connections. Repair or replace damaged wires and ensure all connectors are clean and fully connected.
- 3
Check and replace O2 sensor fuse
Locate the O2 sensor fuse in the fuse box, test it with a multimeter, and replace if blown. Verify the relay is also functioning properly.
- 4
Test PCM and seek professional diagnosis
If sensor and wiring check out, have the PCM tested by a professional technician to rule out internal failure. Advanced diagnostic equipment may be required.
Need a deeper diagnosis?
Search for related repair guides or browse by system.