What it means
The bank 2 sensor 2 oxygen sensor positive current control circuit is below the expected range. The code does not by itself establish a short to ground or predict mixture and fuel-economy effects.
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 positive-current control circuit to operate its pumping cell. The engine control module monitors that circuit and sets P22B9 when its signal falls below the expected range; this points to a low circuit reading but does not identify the cause by itself.
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 check live data for Bank 2 Sensor 2 and related oxygen-sensor codes to see when the low reading occurs.
- Inspect the Bank 2 Sensor 2 connector and harness near the exhaust for corrosion, loose or pushed-back pins, melted insulation, or chafing.
- Check the positive-current control wire for a short to ground or damaged insulation, following the vehicle wiring diagram.
- With the sensor disconnected as directed by the service information, test the harness for continuity and shorts to ground, and compare results with the manufacturer's specification.
- If the wiring and connector pass, test the sensor and control-module circuit according to the manufacturer's diagnostic procedure before replacing parts.
Common fixes
- Repair chafed or shorted wiring in the Bank 2 Sensor 2 positive-current control circuit.
- Clean or repair corroded connector terminals and secure any loose or pushed-back pins.
- Replace the Bank 2 Sensor 2 oxygen sensor if testing identifies an internal fault.
- Repair the control module only if its circuit fault is confirmed by the manufacturer's diagnostic procedure.
Can I keep driving?
You can usually drive cautiously if the engine runs normally, but arrange diagnosis soon because emissions monitoring may be unreliable and fuel use may rise. Avoid prolonged driving if rough running or hesitation worsens.
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.