What it means
The wide-band oxygen sensor on bank 1 sensor 3 reports a pumping current trim circuit low condition. Lambda regulation accuracy is impaired.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 3 is a downstream wide-band oxygen sensor, and its pump-cell trim circuit helps the module interpret exhaust oxygen. This code sets when the circuit is detected low, which can happen if the trim wire is grounded, the sensor has an internal short, or a corroded connection disrupts the circuit.
Common causes
Most likely first.
- Trim wire shorted to ground
- Internal short in pump cell trim
- 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
- Capture freeze-frame data and review Bank 1 Sensor 3 readings to confirm the conditions when the low-circuit fault appeared.
- Inspect the sensor connector and nearby harness for corrosion, moisture, chafing, or contact with ground.
- Check the connector terminals for corrosion and poor pin contact, since added contact resistance can affect the trim circuit.
- Using the manufacturer's wiring information, test the trim wire for an unintended short to ground.
- If the harness and terminals are sound, test the sensor pump-cell trim circuit to check for an internal short.
Common fixes
- Clean and secure corroded Bank 1 Sensor 3 connector terminals where appropriate.
- Repair trim-circuit wiring that is chafed or shorted to ground.
- Replace damaged connector terminals or the connector body.
- Replace Bank 1 Sensor 3 if testing confirms an internal trim-circuit short.
Can I keep driving?
Gentle driving is generally possible if the engine behaves normally, but fuel use and emissions performance may worsen. Have the circuit checked soon, and avoid continued driving if rough running or hesitation becomes pronounced.
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.