What it means
The positive-current control circuit for the oxygen sensor at Bank 1 Sensor 1 is open or malfunctioning. This circuit is used with certain oxygen sensor designs.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
On wide-band oxygen sensor systems, Bank 1 Sensor 1 is the upstream sensor that reports exhaust oxygen to the engine control module for fuel adjustment. The module monitors this sensor’s positive pumping-current control path and sets P2237 when it detects an open or malfunction in that path.
Common causes
Most likely first.
- Pumping current line open
- Wide-band sensor failed
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Read the freeze-frame data and live data for Bank 1 Sensor 1 to see when the fault occurred and whether its readings are missing or implausible.
- With the engine off, inspect the upstream Bank 1 Sensor 1 harness and connector for heat damage, chafing, loose pins, or corrosion.
- Check for exhaust leaks near the Bank 1 Sensor 1 mounting point, since outside air can distort the sensor readings.
- Using the vehicle wiring diagram, check continuity of the positive pumping-current wire from the sensor connector to the control module and look for an open.
- If the wiring and connections are sound, test the wide-band sensor and its related circuits using the manufacturer's procedure before replacing the sensor.
Common fixes
- Reconnect or repair a loose or damaged Bank 1 Sensor 1 connector.
- Repair an open or heat-damaged positive pumping-current wire.
- Repair an exhaust leak near the upstream sensor.
- Replace Bank 1 Sensor 1 if circuit checks confirm an internal sensor failure.
Can I keep driving?
You can usually drive gently for a short time if the engine runs normally, but avoid hard acceleration and prolonged trips. Faulty upstream feedback can worsen fuel economy and emissions, and rough running 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.