What it means
Bank 2 counterpart to P2245. The reference voltage on bank 2, sensor 1 is below the lower threshold — typically a short to ground or failed ECU output.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The upstream wide-band oxygen sensor on bank 2 needs a reference voltage for its exhaust measurement, and the engine control module monitors that feed at Sensor 1. This code sets when the reference voltage is below its expected range, often due to a short to ground, a poor connector contact, or a failed module output.
Common causes
Most likely first.
- Reference line shorted to ground
- ECU reference output failed
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Read freeze-frame data and Bank 2 Sensor 1 live readings to confirm whether the low reference condition is constant or intermittent.
- Inspect the Bank 2 Sensor 1 connector for corrosion and the harness for crushed, rubbed-through, or heat-damaged insulation.
- Trace the bank 2 reference line using the wiring diagram and test for a short to ground or an open circuit.
- Check terminal contact and continuity against the manufacturer's specification, moving the harness gently to look for an intermittent fault.
- If the external circuit passes, test the sensor and module reference output according to the manufacturer's procedure.
Common fixes
- Clean or repair corroded Bank 2 Sensor 1 connector terminals.
- Repair a reference wire shorted to ground or damaged by heat or chafing.
- Replace the Bank 2 Sensor 1 sensor if it fails the specified test and is pulling the circuit low.
- Repair the module reference output if testing confirms it has failed.
Can I keep driving?
The vehicle may be drivable, but unreliable bank 2 upstream feedback can increase fuel consumption and affect idle or emissions. Avoid extended driving if it runs poorly, and have the fault corrected before emissions testing.
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.