What it means
The pumping current of the intake air oxygen sensor on bank 1 reports a circuit low 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 its pump-current circuit helps the module interpret oxygen in the intake stream. This code sets when that circuit signal is too low, pointing to a ground short, an internally shorted pump cell, or a high-resistance connector contact.
Common causes
Most likely first.
- Pump current wire shorted to ground
- Internal short in 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
- Review freeze-frame data and live bank 1 intake oxygen-sensor values for a low or nonresponsive pump-current signal.
- Inspect the bank 1 sensor plug and harness for corrosion, loose pins, damaged insulation, or contact with ground.
- Check that the connector terminals are seated and make good contact, then observe whether the signal changes after securing the plug.
- Use the wiring diagram to test the pump-current circuit for a short to ground and inspect for high-resistance connections.
- If the circuit and terminals pass inspection, test the bank 1 sensor pump cell against the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose bank 1 sensor connector terminals.
- Repair damaged wiring or a short to ground in the pump-current circuit.
- Replace the bank 1 intake air oxygen sensor if its pump cell is shorted.
- Clear the code and verify the pump-current signal returns to a plausible range.
Can I keep driving?
The engine may continue to run, but inaccurate bank 1 intake oxygen feedback can raise fuel consumption and emissions. Keep driving limited if rough idle or hesitation occurs, and correct 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.