What does P0038 mean?
Oxygen sensors only work when they are hot (around 600 F or more). Each one has a small electric heater so it can start reading soon after a cold start. This code means the computer found a problem in the heater circuit for the bank 1, sensor 2 (downstream, after the catalytic converter) oxygen sensor.
The signal is reading higher than the sensor can normally produce, which points at a wiring fault or a dead sensor.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Usually no drivability change
- Fuel economy may drop slightly after cold starts
- Can stop the car passing an emissions test
Common causes
- Open sensor ground wire
- Signal wire shorted to the 5 V reference or to battery voltage
- Water in the connector
- Failed sensor
How to diagnose P0038
- Check the sensor ground first: an open ground drives the signal high.
- Unplug the sensor: if the signal still reads high, look for a short to voltage in the harness.
- If the wiring is good, replace the sensor.
- Check the O2 heater fuse first.
- Unplug the sensor and measure heater resistance across the two heater pins (usually the two same-colored wires). Many heaters read roughly 2 to 15 ohms. Open means the heater is dead.
How to fix it
- Replace the fuse and find out why it blew if it is open
- Repair damaged wiring
- Replace the oxygen sensor if the heater is open
Estimated repair cost
Likely repairs for P0038 run from about $50 to $450, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Oxygen / A/F sensor replacement | $150 - $450 |
| Fuse or wiring repair for sensor heater | $50 - $250 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0038?
Low severity
Usually safe to drive. Get it fixed before your next emissions test.
P0038 FAQ
What does P0038 mean?
P0038 stands for "HO2S Heater Control Circuit High (Bank 1 Sensor 2)". Oxygen sensors only work when they are hot (around 600 F or more).
Can I drive with a P0038 code?
Usually safe to drive. Get it fixed before your next emissions test.
How much does it cost to fix P0038?
It depends on the cause. The likely repairs for P0038 range from about $50 to $450 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0038?
The most common causes are: open sensor ground wire; signal wire shorted to the 5 V reference or to battery voltage; water in the connector.