VOLVO
ECM-0134 - Front heated oxygen sensor (HO2S), bank 1. Signal missing
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module has registered that the signal from the front lambda sensor on bank 1 is missing and treats this as a fault. Without the signal the control module cannot read the exhaust, so it cannot track the fuel-air mixture. The usual cause is an open or shorted signal wire, or a damaged sensor.
Possible causes
- Open circuit in the signal wire
- Signal wire shorted to ground
- Signal wire shorted to supply voltage
- Signal wire shorted to reference voltage
- Damaged front lambda sensor
- Damaged control module
What you can do
- 1Read, note and clear the code, then road test to see whether it returns
- 2Check that the connector at the lambda sensor is fully engaged and free from corrosion
- 3Follow the signal wire from the sensor and look for breaks, chafing and pinched sections, especially near the exhaust pipe
- 4With the sensor connector unplugged, use a multimeter to check that the signal wire has no connection to ground (the body)
- 5If you have a diagnostic tool, check in live data whether the lambda sensor value changes while the engine runs. A value that never changes points to a missing signal
- 6If the fault returns, have a workshop with diagnostic equipment check the control module and the sensor
Symptoms you may notice1
- Malfunction indicator lamp (MIL) lit
General guidance for car owners. Diagnosis on the car can point to a different cause.