What it means
The wide-band oxygen sensor on bank 1 sensor 3 reports a pumping current trim circuit high 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 supports the module's interpretation of exhaust oxygen. This code sets when the circuit is detected high, which can result from a signal wire shorted to battery voltage or a sensor or wiring fault.
Common causes
Most likely first.
- Signal wire shorted to B+
- Internal sensor or circuit fault
- Connector or wiring fault
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 compare Bank 1 Sensor 3 live readings with other sensor data to understand when the high-circuit fault occurs.
- Inspect the sensor connector and harness for damaged insulation, loose terminals, or wiring that could contact a power source.
- Using the manufacturer's wiring diagram, check whether the relevant signal wire is shorted to battery voltage.
- Inspect the connector terminals for damage or poor fit and check circuit continuity as directed by the manufacturer.
- If the wiring and connector pass inspection, test Bank 1 Sensor 3 and its trim circuit using the manufacturer's procedure.
Common fixes
- Secure loose wiring and repair insulation that allows the signal wire to contact a power feed.
- Repair or replace a damaged connector or terminal.
- Repair the affected signal-circuit wiring.
- Replace Bank 1 Sensor 3 if testing identifies an internal sensor or trim-circuit fault.
Can I keep driving?
If the vehicle runs normally, a short gentle trip for diagnosis is usually reasonable, but the fault can impair emissions control and increase fuel use. Stop driving if the engine begins to run roughly or loses power.
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.