VOLVO
ECM-0172 - Long-term fuel trim, bank 1. 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:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
Fuel trim on bank 1 is below the set value, so the fuel-air mixture is too rich, and the control module logs a fault when the deviation becomes too large. Possible causes include a blocked air intake, damaged injectors, or leaks in the exhaust or vacuum system.
Possible causes
- Blocked inlet manifold
- Damaged injectors
- Leak in the exhaust system
- Leak in the vacuum system
What you can do
- 1Read the fault code, clear it and road test to see whether it returns
- 2Check that the air intake and inlet pipe are not blocked by dirt or debris
- 3With the engine warm, listen for exhaust leaks and check the vacuum hoses for cracks and loose connections
- 4With a diagnostic tool, check the fuel adaptation in live data when warm. A value that stays constantly low confirms the fault
- 5Have a workshop with diagnostic equipment check the injectors for function, damage and leaks
- 6After the repair the adaptations may need resetting, which a workshop does with diagnostic equipment
Symptoms you may notice1
- Malfunction indicator lamp (MIL) lit
General guidance for car owners. Diagnosis on the car can point to a different cause.