What it means
An open or fault is detected in the positive current control circuit for the Bank 1 Sensor 3 oxygen sensor. This can interfere with the sensor's air-fuel measurement.
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 counted along the exhaust on the engine's Bank 1 side; its positive-current control circuit is part of the sensor's measurement electronics. The control module sets P2A38 when it detects an open or electrical fault in that positive-current circuit, which can make the sensor's air-fuel information unreliable.
Common causes
Most likely first.
- Open or damaged wiring
- Faulty oxygen sensor
- Poor connector contact
Symptoms
- Check-engine light
How to diagnose it
- Record freeze-frame data and inspect Bank 1 Sensor 3 live data for implausible or missing readings when the fault was set.
- Locate Bank 1 Sensor 3 using vehicle information, then inspect its connector and nearby harness for heat damage, chafing, moisture, or loose pins.
- Check the positive-current control wire for continuity and connector contact using the manufacturer's wiring diagram and procedure.
- Test the circuit for unintended shorts to ground or power and compare sensor electrical checks with the manufacturer's specification.
- If wiring and connections pass, test Bank 1 Sensor 3 itself and confirm the control module circuit before replacing parts.
Common fixes
- Reconnect or repair a loose Bank 1 Sensor 3 connector.
- Repair damaged or open wiring in the sensor's positive-current control circuit.
- Replace Bank 1 Sensor 3 if its positive-current control circuit fails the specified test.
- Repair a confirmed control-module connector or circuit fault.
Can I keep driving?
The check-engine light may be on, and emissions control can be affected even if the vehicle feels normal. Limit unnecessary driving and arrange diagnosis soon; stop if it begins running 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.