VOLVO
ECM-220D - Rear heated oxygen sensor (HO2S). Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (5)
What does this fault code mean?
The engine control module checks how fast the rear sensor reacts during a fuel cut-off, as the mixture changes from rich to lean. The code is stored if the sensor voltage drops too slowly over more than ten consecutive fuel shut-offs in the same driving cycle, and the cause can be poor contact or a damaged sensor.
Possible causes
- Contact resistance, oxidation or poor contact in the connections
- Damaged rear oxygen sensor
What you can do
- 1Clear the code and road test the car to see whether it returns
- 2Check the connector on the rear sensor for poor contact, contact resistance and oxidation, and do not use rust solvent spray or grease in it
- 3If the connector is clean and secure but the fault remains, have a workshop try a new rear oxygen sensor
Symptoms you may notice1
- The malfunction indicator lamp (MIL) comes on
General guidance for car owners. Diagnosis on the car can point to a different cause.