DTC 2-3-1 Long Term Fuel Trim, Part Load
2-3-1 LONG TERM FUEL TRIM PARTIAL LOADPrecondition for DTC
^ The control module receives information from the Heated Oxygen Sensor (HO2S) about the fuel/air mixture in the idling and partial load ranges. If the fuel/air mixture deviates from Lambda=1 the short term fuel trim will compensate this by adjusting the injection timing so that Lambda=1 is achieved. When the short term fuel trim carries out this adjustment, its mid-point must be adapted by the long term trim. When the long term fuel trim has adapted the short term trim to a maximum value, DTC 2-3-2 (idling range -0.48 ms to +0.40 ms) or DTC 2-3-1 (partial load range 0.773 to 1.227) and status message Upper Limit (lean fuel/air mixture) or Lower Limit (rich fuel/air mixture) will be set.
Substitute values
^ None.
Fault sources
^ Upper limit:
- Defective Mass Air Flow (MAF) sensor.
- Low fuel pressure.
- Air leakage.
- Faulty sensor signals.
^ Lower limit:
- Defective Mass Air Flow (MAF) sensor.
- Air leakage.
- High fuel pressure.
- Leaking injectors.
- Leaking EVAP system.
- Dirty engine oil.
- Oil level too high.
- Faulty sensor signals.
Fault symptoms
^ Can result in high fuel consumption.
^ Can result in impaired performance.