VOLVO
ECM-24EC - Rear heated oxygen sensor (HO2S). Slow regulation
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 (9)
- Volvo C30 (2007–2013)2007Engine B5254T3 only
- Volvo C30 (2007–2013)2008–2013Engine B5254T7 only
- Volvo C70 (2006–2013)2006–2007Engine B5254T3 only
- Volvo C70 (2006–2013)2008–2013Engine B5254T7 only
- Volvo S40 (2004–2013)2006–2007Engine B5254T3 only
- Volvo S40 (2004–2013)2008Engine B5254T3, B5254T7 only
- Volvo S40 (2004–2013)2009–2012Engine B5254T7 only
- Volvo V50 (2004–2013)2006–2007Engine B5254T3 only
- Volvo V50 (2004–2013)2008–2012Engine B5254T7 only
What does this fault code mean?
The engine control module (ECM) measures how quickly the rear oxygen sensor responds to changes in the fuel/air mixture. If the response is too slow, the module treats it as a fault and the code is set. The fault concerns the sensor's response time, not the mixture itself.
Possible causes
- Contact resistance or oxidation at the connections
- Damaged rear oxygen sensor
What you can do
- 1Clear the code and road test to see whether it comes back
- 2Look at the rear sensor connector for oxidation or poor contact. Rust solvent spray and grease must not be used on it
- 3If the connector is in good condition but the fault remains, have a workshop try a new rear oxygen sensor
Symptoms you may notice1
- The malfunction indicator lamp (MIL) is lit
General guidance for car owners. Diagnosis on the car can point to a different cause.