What it means
The bank 1 sensor 2 oxygen sensor reference voltage does not meet the expected performance criteria. The code does not by itself identify the cause.
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 oxygen sensor downstream of the catalytic converter on the bank containing cylinder 1. The control module checks its reference-voltage behavior as part of monitoring the sensor circuit; this code sets when that behavior does not meet the expected performance criteria, without identifying the cause.
Common causes
Most likely first.
- Faulty downstream oxygen sensor
- Damaged or corroded sensor wiring or connector
- Poor sensor ground or reference circuit connection
- Exhaust leak near the sensor
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Record freeze-frame data and compare live readings for Bank 1 Sensor 2 with the upstream sensor and the manufacturer's expected behavior to see when the performance fault occurs.
- Inspect the downstream sensor, its connector, and nearby harness for heat damage, corrosion, loose pins, or poor ground and reference connections.
- Check the exhaust around Bank 1 Sensor 2 for leaks that could affect the sensor's readings.
- With the wiring diagram, test the sensor's reference and ground circuits for continuity and unwanted resistance, using the manufacturer's procedure.
- If wiring and exhaust checks pass, test the downstream sensor against the manufacturer's specification before replacing it.
Common fixes
- Repair a loose, corroded, or damaged Bank 1 Sensor 2 connector.
- Repair damaged wiring or restore a poor ground or reference connection.
- Repair an exhaust leak near the downstream sensor.
- Replace Bank 1 Sensor 2 if it fails the manufacturer's tests.
Can I keep driving?
If the engine runs normally and the warning light is steady, a short, gentle drive is usually possible, but arrange diagnosis soon and avoid hard acceleration. Poor sensor readings can affect fuel economy and emissions, 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.