VOLVO
ECM-0038 - Rear heated oxygen sensor (HO2S), bank 1 heating. Signal too high
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The ECM watches the heater circuit of the rear oxygen sensor on bank 1. The voltage in the heater circuit is higher than allowed, which the ECM treats as a fault. Most often the signal wire is shorted to supply voltage, but the sensor itself may also be damaged.
Possible causes
- Signal wire shorted to supply voltage
- Damaged rear oxygen sensor
What you can do
- 1With the ignition off, unplug the rear oxygen sensor connector and check the contacts for looseness, contact resistance and oxidation
- 2With the ignition on and the connector unplugged, measure the heater signal wire with a multimeter; voltage there indicates a short to supply voltage
- 3If the fault remains after erasing codes and a test drive, have a workshop check and replace the oxygen sensor if needed
Symptoms you may notice1
- Malfunction indicator lamp (MIL) lights up
General guidance for car owners. Diagnosis on the car can point to a different cause.