VOLVO
ECM-B20A - Long-term fuel trim. Lower limit
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS70 (1997–2000), V70 (1997–2000)
Show models by year and engine (2)
What does this fault code mean?
This code applies to the lower limit of the adaptive lambda control when the car runs on gas. It means the control module has reached its lowest correction value for the fuel mixture and cannot compensate any further. Gas operation is disabled, and the engine does not run on gas.
Possible causes
- Blocked gas filter
- Low fuel level in the gas tank
What you can do
- 1Check that there is enough gas in the gas tank, since the code can be caused by a low gas level
- 2Make sure the hose from the intake manifold to the pressure regulator sits correctly, and that fittings and hose do not leak
- 3Check the gas filter and replace it if needed
- 4If the fault remains after the other checks, have a workshop check the gas pressure
- 5If you have a diagnostic tool: read the lambda value in live data with the engine idling on gas and check that it is stable and close to normal
Symptoms you may notice1
- The engine does not run on gas
What the fault can affect1
- Gas operation is disabled
General guidance for car owners. Diagnosis on the car can point to a different cause.