What it means
O2 negative current line on bank 2 sensor 2 stuck high — short to B+. 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
The wide-band oxygen sensor after the Bank 2 catalytic converter uses a negative-current control line as the sinking side of its pumping-current circuit. The engine control module sets P22C1 when that circuit reads above its expected range, which may indicate an unwanted connection to battery voltage.
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
- Record freeze-frame data and check Bank 2 Sensor 2 live data and related codes to establish when the negative-current reading is high.
- Inspect the negative-current wire and connector for corrosion, damaged pins, melted insulation, or contact with a powered wire.
- Use the wiring diagram to check whether the Bank 2 Sensor 2 negative-current circuit is shorted to battery voltage.
- With the sensor disconnected as directed by service information, test the harness for shorts to voltage and continuity against the manufacturer's specification.
- If the harness checks out, test the sensor and control-module circuit according to the manufacturer's diagnostic procedure.
Common fixes
- Repair a negative-current wire shorted to battery voltage or pinched against a power source.
- Clean or repair corroded connector contacts and damaged terminals.
- Replace the Bank 2 Sensor 2 oxygen sensor if testing identifies an internal circuit fault.
- Repair the control module only if its fault is confirmed by the manufacturer's procedure.
Can I keep driving?
If the engine runs normally, cautious driving while arranging diagnosis is usually reasonable, though emissions monitoring may not work correctly. Stop driving if it develops pronounced hesitation or rough running.
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.