What it means
The control module detects that the signals for oxygen sensors 1 and 2 on bank 2 appear to be reversed. This can occur if their connections are crossed; the code does not identify the repair history.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 has an upstream oxygen sensor (Sensor 1) and a downstream oxygen sensor (Sensor 2); the control module uses their signals to manage fueling and assess exhaust treatment. This code sets when the signal patterns indicate that the two bank 2 sensor connections may be reversed.
Common causes
Most likely first.
- Sensor 1 and 2 connectors crossed
- Wiring connected incorrectly
- Incorrect sensor installation
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Check freeze-frame data and live oxygen-sensor readings to see whether bank 2 Sensor 1 and Sensor 2 behave in the opposite positions from what the module expects.
- Inspect the bank 2 Sensor 1 and Sensor 2 connectors and harness routing for crossed plugs, damage, corrosion, or loose contacts.
- Confirm that each sensor is installed in its intended upstream or downstream bank 2 location and that the connectors reach the correct sensors without strain.
- With the wiring diagram, trace each bank 2 sensor circuit to the correct module terminals and check for crossed or incorrectly repaired wiring.
- If connections and wiring are correct, test both bank 2 sensor signals and their circuits against the manufacturer's specifications to identify a sensor or circuit fault.
Common fixes
- Reconnect crossed bank 2 Sensor 1 and Sensor 2 plugs to their correct sensors.
- Repair damaged, incorrectly joined, or crossed bank 2 sensor wiring.
- Correct an incorrectly installed bank 2 oxygen sensor.
- Replace a faulty bank 2 sensor or repair its circuit if testing confirms the fault.
Can I keep driving?
Usually you can drive cautiously if the engine runs normally, but avoid unnecessary trips because incorrect bank 2 sensor feedback can increase fuel use and emissions. Stop if the engine runs very roughly or loses power.
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.