What it means
The heater control circuit for the Bank 1 Sensor 2 heated oxygen sensor is reporting voltage above the expected 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 2 is the heated oxygen sensor downstream of the catalytic converter on the cylinder 1 side of the engine. The module monitors its heater control circuit and sets P0038 when the circuit voltage is higher than expected, which can happen if a wire contacts a power supply.
Common causes
Most likely first.
- Heater wire shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light on
- Oxygen-sensor heater may warm slowly
- Fuel economy may decrease
- Emissions may increase
How to diagnose it
- Record freeze-frame data and check heater command and sensor readings with a scan tool to see when the high-voltage fault occurs.
- Inspect the Bank 1 Sensor 2 connector and harness for corrosion, pin damage, or insulation melted or pinched against a power source.
- Check whether the heater control wire is shorted to battery voltage or another supply, following the manufacturer's circuit information.
- With the circuit safely isolated as specified by the manufacturer, test the wiring for continuity and unintended connection to a supply.
- Test the sensor heater and control circuit against the manufacturer's specification to determine whether the fault lies in the sensor, harness, or control side.
Common fixes
- Repair a pinched or chafed wire that is contacting a power supply.
- Clean or repair corroded Bank 1 Sensor 2 connector terminals.
- Replace the Bank 1 Sensor 2 oxygen sensor if its heater fails testing.
- Repair the heater control circuit if tests confirm an unintended supply connection.
Can I keep driving?
If the engine runs normally, gentle driving is generally possible, but fix the fault soon because the sensor heater may not work correctly and emissions can increase. Avoid prolonged driving if fuel economy worsens or the engine starts running roughly.
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.