What it means
The wide-band oxygen sensor on bank 1 sensor 3 reports a pumping current trim circuit/open 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 whose pump-cell trim circuit helps the control module interpret oxygen content in the exhaust. This code sets when the module detects an open in that trim circuit, so lambda regulation based on this sensor may be less accurate.
Common causes
Most likely first.
- Open in trim wire
- Internal open in pump cell trim
- Pin pushed back out of connector body
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Use a scan tool to record freeze-frame data and compare Bank 1 Sensor 3 readings with other oxygen-sensor data to see when the fault occurred.
- Inspect the Bank 1 Sensor 3 connector for a pushed-back pin, poor seating, or damaged wiring near the exhaust.
- With the system powered down as specified by the manufacturer, check the trim-circuit wiring for an open between the sensor connector and the control module.
- Check connector pin fit and continuity through the relevant circuit using the manufacturer's wiring information.
- If wiring and connector checks pass, test the sensor's pump-cell trim circuit according to the manufacturer's procedure to identify an internal open.
Common fixes
- Reconnect the Bank 1 Sensor 3 connector and secure any loose wiring.
- Repair an open or damaged trim-circuit wire.
- Repair or replace a connector with a pushed-back or damaged terminal.
- Replace Bank 1 Sensor 3 if its internal trim circuit is open.
Can I keep driving?
You can usually drive gently if the vehicle runs normally, but arrange diagnosis soon because lambda accuracy and emissions performance may be affected. Stop if the engine runs poorly or hesitation becomes severe.
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.