VOLVO
ECM-28C0 - Heated oxygen sensor (HO2S). Signal too low
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:
8 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), S60 (2001–2009), V50 (2004–2013), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
Show models by year and engine (20)
- Volvo C30 (2007–2013)2007Engine D5244T8, D5244T9 only
- Volvo C30 (2007–2013)2008–2010Engine D5244T13, D5244T8, D5244T9 only
- Volvo C70 (2006–2013)2007Engine D5244T8, D5244T9 only
- Volvo C70 (2006–2013)2008–2010Engine D5244T13, D5244T8, D5244T9 only
- Volvo S40 (2004–2013)2006Engine D5244T8 only
- Volvo S40 (2004–2013)2007Engine D5244T8, D5244T9 only
- Volvo S40 (2004–2013)2008–2010Engine D5244T13, D5244T8, D5244T9 only
- Volvo S60 (2001–2009)2006Engine D5244T4, D5244T5, D5244T6, D5244T7 only
- Volvo S60 (2001–2009)2007–2009Engine D5244T4, D5244T5, D5244T7 only
- Volvo V50 (2004–2013)2006Engine D5244T8 only
- Volvo V50 (2004–2013)2007Engine D5244T8, D5244T9 only
- Volvo V50 (2004–2013)2008–2010Engine D5244T13, D5244T8, D5244T9 only
- Volvo V70 (2000–2008)2006Engine D5244T4, D5244T5, D5244T6, D5244T7 only
- Volvo V70 (2000–2008)2007Engine D5244T4, D5244T5, D5244T7 only
- Volvo V70 (2000–2008)2008Engine D5244T5, D5244T7 only
- Volvo V70 XC / XC70 (2001–2007)2006–2007Engine D5244T4 only
- Volvo XC90 (2003–)2006–2007Engine D5244T4 only
- Volvo XC90 (2003–)2008–2010Engine D5244T4, D5244T5 only
- Volvo XC90 (2003–)2011Engine D5244T18, D5244T4, D5244T5 only
- Volvo XC90 (2003–)2012All engines except: B5254T2, B6324S5
What does this fault code mean?
The engine control module (ECM) receives the oxygen sensor signal about the fuel and air mixture. The code is set when that signal is judged wrong, here too low. The fault is detected while driving under load, and the cause may be a short to ground in the signal wire, a damaged sensor or a fault inside the control module.
Possible causes
- Signal cable shorted to ground
- Damaged heated oxygen sensor
- Fault inside the control module
What you can do
- 1Read the code, clear it and drive under load, for example up a hill, to see whether it returns
- 2Switch off the ignition, unplug the oxygen sensor connector and look for oxidation, play and loose connections
- 3With the car switched off, use a multimeter to check that the signal cable is not shorted to ground
- 4If you have a diagnostic tool: watch the oxygen sensor value in live data as the engine is loaded, and see whether it sticks at a low value
- 5If the wiring is in order but the fault remains, have a workshop check the sensor and the control module with diagnostic equipment
Symptoms you may notice1
- Message in the information display
General guidance for car owners. Diagnosis on the car can point to a different cause.