P0038: Oxygen sensor heater circuit high (bank 1, sensor 2)
The ECU sees too high a voltage in the heater of the rear oxygen sensor on bank 1; usually a wire, the connector or the sensor.
| Code | P0038 |
|---|---|
| System | Engine and transmission |
| Group | P00xx, Air, fuel and emissions |
| Type | Generic: it means the same on every make |
| Can you keep driving? | Yes, no rush |
What P0038 means
An oxygen sensor (lambda sensor) only reads accurately when very hot, so it has a built-in heater that warms it up as soon as the engine starts. The ECU sees a higher voltage than normal in that circuit, nearly always from an electrical fault: a bare wire, the connector, the earth or the heater element itself. This sensor sits after the catalytic converter on bank 1 and is used to check that the catalytic converter is working.
Most common causes
- Damp connector or bridged terminals
- Bare wire touching a positive feed
- Short circuit in the sensor’s heater element
- Poor heater earth
- Fault in the ECU’s control circuit (uncommon)
Symptoms
- Engine warning light on
- Usually no change in how the car drives
- Possible inspection failure because of the warning light
Can you drive with P0038?
Yes, no rush You can drive normally, as this sensor plays no part in the fuel mixture. Just get it fixed before the next inspection.
Open the bonnetthe in-depth explanation
How to check it
Start by checking the oxygen sensor heater fuse in the fuse box. With the engine cold and the sensor unplugged, a multimeter across the two heater terminals should show a low resistance; if it reads nothing, the sensor has failed.
How to read and clear P0038 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0038 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P0034 The turbo A discharge valve control gives a lower signal than normal
- P0035 The turbo A discharge valve control gives a higher signal than normal
- P0036 Oxygen sensor heater circuit fault (bank 1, sensor 2)
- P0037 Oxygen sensor heater circuit low (bank 1, sensor 2)
- P0039 The turbo A discharge valve control gives readings outside the normal range
- P003A The variable geometry turbo actuator has exceeded its learning limit
- P003B The actuator of the second turbo has exceeded its learning limit
- P003C Intake camshaft profile control A on bank 1 performs poorly or remains off
- P0010 Camshaft A actuator control: open circuit (bank 1)
- P0011 Camshaft A timing over-advanced (bank 1)
- P0012 Camshaft A timing over-retarded (bank 1)
- P0013 Camshaft B actuator control: open circuit (bank 1)
What does code P0038 mean?
An oxygen sensor (lambda sensor) only reads accurately when very hot, so it has a built-in heater that warms it up as soon as the engine starts. The ECU sees a higher voltage than normal in that circuit, nearly always from an electrical fault: a bare wire, the connector, the earth or the heater element itself. This sensor sits after the catalytic converter on bank 1 and is used to check that the catalytic converter is working.
Can you drive with P0038?
You can drive normally, as this sensor plays no part in the fuel mixture. Just get it fixed before the next inspection.
How do you clear P0038?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0038 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
