What it means
The positive current control circuit for the Bank 1 Sensor 3 oxygen sensor is above its expected electrical range.
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 the third oxygen sensor position on the engine's Bank 1 exhaust side, and its positive-current control circuit supports the sensor's measurement function. P2A3A sets when circuit voltage rises above the expected range, often because the wire is shorted to voltage or the sensor circuit has failed.
Common causes
Most likely first.
- Wiring short to voltage
- Faulty oxygen sensor
- Poor connector contact
Symptoms
- Check-engine light
How to diagnose it
- Record freeze-frame data and check Bank 1 Sensor 3 live data for an abnormal reading coinciding with the high-circuit fault.
- Inspect the sensor connector and harness for damaged insulation contacting a power feed, heat damage, corrosion, or loose terminals.
- With the sensor disconnected as directed, test the positive-current control wire for a short to voltage.
- Check connector contacts and the sensor circuit against the manufacturer's procedure and specification.
- If wiring and connectors pass, test Bank 1 Sensor 3 and verify the module circuit before replacing parts.
Common fixes
- Repair the positive-current control wire if it is shorted to a power feed.
- Clean or repair poor contact at the Bank 1 Sensor 3 connector.
- Replace Bank 1 Sensor 3 if its positive-current circuit fails the specified test.
- Repair a confirmed control-module circuit fault.
Can I keep driving?
The fault can make Bank 1 Sensor 3 data unreliable and increase emissions, even if the vehicle seems to drive normally. Arrange diagnosis soon and stop if the engine runs poorly or the warning light flashes.
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.