What it means
O2 trim line on bank 2 sensor 2 stuck low — short to ground. A drifted or sluggish lambda sensor lets the mixture run lean or rich without correction — fuel economy and emissions suffer immediately.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 2 is the oxygen sensor after the catalytic converter on the engine's second cylinder bank. Its pumping-current trim circuit lets the control module adjust how it interprets the sensor signal; this code sets when that circuit reads below its expected range, often from a short to ground.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
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 2 Sensor 2 with the other oxygen sensors to see whether the fault is persistent.
- Inspect the Bank 2 Sensor 2 connector and nearby harness for corrosion, damaged pins, or insulation rubbed through against ground.
- With the wiring diagram, check the trim circuit for a short to ground and inspect connector pin fit.
- Test circuit continuity and resistance with the sensor and module disconnected as specified by the manufacturer.
- If the wiring and connections pass, test Bank 2 Sensor 2 and its circuit against the manufacturer's diagnostic procedure.
Common fixes
- Repair chafed wiring shorted to ground.
- Clean or repair corroded or poorly seated connector pins.
- Replace damaged sections of the Bank 2 Sensor 2 harness.
- Replace Bank 2 Sensor 2 if it fails the specified test.
Can I keep driving?
If the engine runs normally, a short, cautious drive to a repair location is usually possible, but avoid hard acceleration and long trips. Fuel economy and emissions may worsen, and a rough-running engine should be checked promptly.
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.