What it means
The bank 1 sensor 2 oxygen sensor reference voltage is above the expected range. The code does not by itself establish a short to voltage or predict mixture effects.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 2 is the downstream oxygen sensor on the bank containing cylinder 1. The control module monitors its reference-voltage circuit and sets this code when the voltage rises above the expected range; that reading alone does not establish a short to battery voltage or predict mixture effects.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Save freeze-frame data and compare live Bank 1 Sensor 2 readings with the manufacturer's expected range to confirm when the high-circuit fault occurs.
- Inspect the sensor connector and harness for corrosion, displaced pins, or wiring pinched against a power source.
- Use the wiring diagram to identify the reference circuit and check for an unintended connection to battery voltage.
- Check terminals for corrosion or poor contact, which can disrupt the circuit reading.
- Test the reference circuit and downstream sensor using the manufacturer's procedure before deciding which part has failed.
Common fixes
- Repair corroded or loose Bank 1 Sensor 2 connector terminals.
- Repair wiring pinched against a power source or otherwise damaged.
- Correct a confirmed short to battery voltage in the reference circuit.
- Replace the downstream sensor if it fails the manufacturer's tests.
Can I keep driving?
If the engine runs normally and the check-engine light is steady, keep driving to a minimum and avoid hard acceleration until the circuit is checked. Fuel economy and emissions monitoring may suffer, and the vehicle may fail an emissions test.
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.