What it means
The positive-current control circuit for the oxygen sensor at Bank 1 Sensor 1 is above its expected range. The code identifies a circuit condition, not a confirmed failed sensor.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module uses Bank 1 Sensor 1, the upstream wide-band oxygen sensor, to guide fuel mixture adjustments. P2239 indicates that the sensor’s positive pumping-current control circuit is above its expected range, which can happen if the line is shorted to a supply or its return path is open.
Common causes
Most likely first.
- Pump line shorted to supply
- Return path to ECU open
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Review freeze-frame and live data for Bank 1 Sensor 1 to identify when the high-circuit reading appears and whether it is steady or intermittent.
- Inspect the upstream sensor connector and harness for heat damage, corrosion, spread pins, or contact with the exhaust.
- Check the wiring diagram and test the positive pumping-current line for a short to a supply voltage.
- Check continuity of the circuit return path to the control module and inspect both ends for poor connections or an open.
- If the wiring checks pass, test Bank 1 Sensor 1 and related circuits using the manufacturer's procedure.
Common fixes
- Secure or repair loose, corroded, or damaged Bank 1 Sensor 1 connector contacts.
- Repair the positive pumping-current wire if it is shorted to a supply.
- Restore an open or damaged return path between the sensor and control module.
- Replace Bank 1 Sensor 1 only if circuit testing confirms an internal sensor fault.
Can I keep driving?
If the engine runs normally, drive only as needed and avoid heavy acceleration or long trips. Incorrect upstream oxygen feedback can increase fuel use and emissions; have the circuit checked soon, especially if hesitation or rough idle develops.
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.