What it means
The trim adjustment for 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 module monitors a trim circuit to control its pumping current. This code sets when the circuit signal is too high, which may result from a short to battery voltage, an open pump cell, or a poor connector contact.
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
- Save freeze-frame data and review live bank 1 intake oxygen-sensor data for a high or fixed pump-current trim signal.
- Inspect the bank 1 sensor connector and wiring for corrosion, a loose or pushed-back pin, or insulation damage that could let the circuit contact battery power.
- Check the harness route for chafing or contact with powered wiring, then secure any loose sections.
- Use the wiring diagram to test for a short to battery voltage and check the pump-current trim circuit for an open.
- If the circuit checks out, test the bank 1 sensor pump cell against the manufacturer's specification.
Common fixes
- Clean and secure a corroded or loose bank 1 sensor connector.
- Repair wiring shorted to battery voltage or an open in the trim circuit.
- Replace the bank 1 intake air oxygen sensor if its pump cell is open or fails testing.
- Clear the code and verify that bank 1 sensor data is plausible.
Can I keep driving?
The vehicle may be driveable, but bank 1 intake oxygen feedback may be unreliable, increasing fuel use and emissions. Avoid long trips if the engine hesitates or runs roughly, 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.