VOLVO
ECM-258C - Front heated oxygen sensor (HO2S), bank 2. Signal too high
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS80 (1999–2006), XC90 (2003–)
Show models by year and engine (2)
What does this fault code mean?
The engine control module (ECM) detects that the signal wires to the oxygen sensor on bank 2 are shorted to supply voltage. Although the fault shows as a signal that is too high, the cause lies in the wiring or the sensor.
Possible causes
- Signal wires shorted to supply voltage
- Damaged oxygen sensor on bank 2
What you can do
- 1Read the code, clear it and road test the car to see whether it returns
- 2Check that the connector at the lambda sensor is fully engaged and clean. No rust solvent spray or grease in the connector
- 3With the control module disconnected, use a multimeter to check that the signal wires have no contact with supply voltage
- 4Look for chafed spots on the wires where they may have touched a live wire or been pinched
- 5If the wiring is intact the sensor may be damaged; have a workshop check or replace it
Symptoms you may notice1
- Malfunction indicator lamp (MIL) on
General guidance for car owners. Diagnosis on the car can point to a different cause.