What it means
The pumping current of the intake air oxygen sensor on bank 1 reports a circuit high condition. Wide-band lambda regulation on the intake side is impaired.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The bank 1 intake air oxygen sensor uses a wide-band pump cell, and the control module monitors its pumping-current circuit to regulate oxygen measurement. This code sets when the circuit signal is too high, commonly due to a short to battery voltage, an open pump cell, or a connector contact problem.
Common causes
Most likely first.
- Pump current wire shorted to B+
- Open pump cell
- 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
- Record freeze-frame data and check live bank 1 intake oxygen-sensor values for a high or fixed pump-current signal.
- Inspect the bank 1 sensor connector for corrosion, loose or pushed-back pins, and wiring damage that could expose the circuit to battery power.
- Trace the harness for chafing or contact with powered wires, and secure or repair any damaged section.
- Using the wiring diagram, check the pump-current circuit for a short to battery voltage and for an open.
- If the harness and connector are sound, test the bank 1 sensor pump cell against the manufacturer's specification.
Common fixes
- Clean and firmly reconnect corroded or loose bank 1 sensor terminals.
- Repair a short to battery voltage or open wiring in the pump-current circuit.
- Replace the bank 1 intake air oxygen sensor if the pump cell is open or fails testing.
- Clear the code and confirm bank 1 oxygen-sensor data is plausible.
Can I keep driving?
The vehicle may remain driveable, but bank 1 intake oxygen feedback can be unreliable and fuel use or emissions may increase. Avoid long trips if the engine runs roughly or hesitates, and repair the fault before an emissions inspection.
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.