VOLVO
ECM-440A - Long-term fuel trim. Upper limit
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 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008)
What does this fault code mean?
The engine control module receives information from the oxygen sensor that the mixture shifts around λ=1 during closed-loop control. If the sensor sticks at the upper limit, meaning a rich mixture, for longer than permitted, the fault code is set and gas power is disabled.
Possible causes
- Incorrect gas pressure or damaged pressure regulator
- Fault in the wiring harness
- Damaged fuel shut-off valve or stepper motor
- Clogged or damaged fuel distributor
- Damaged mass air flow sensor
What you can do
- 1Have a workshop measure the gas pressure, since incorrect pressure can give a rich mixture
- 2Look for a damaged wiring harness or loose connectors in the gas system wiring
- 3Have a workshop check the fuel distributor, the stepper motor and the fuel shut-off valve if the fault remains
- 4Have a workshop check the mass air flow sensor and replace it if it is damaged
- 5Clear the fault code after the repair and test drive the car on gas
Symptoms you may notice2
- The engine will not operate on gas
- Switch to gas power is not possible
What the fault can affect1
- Gas power is disabled
General guidance for car owners. Diagnosis on the car can point to a different cause.