General Description
In order to provide the best possible combination of drivability, fuel economy and emission control, the PCM uses a closed loop air/fuel metering system. The PCM monitors the HO2S signal voltage and adjusts fuel delivery based it in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The PCM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The PCM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition.
DTC Description
Checking the fuel trime value at idle under detecting condition, if its average exceeds the limit over certain period, PCM sets P2189. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | ? Monitor the fuel trim value at idle | ? Air leakage ? Improper fuel pressure ? PCV valve stuck ? Clogging of injector |
Enable Conditions | ? Engine warm-up sufficiently ? Engine running under Idle state over 5 minutes ? 60°C(140°F) = Engine coolant temperature = 115°C(239°F) ? No disabling faults (DTCs related to HO2S, purge valve,catalyst ) | |
Threshold value | ? Average of short term fuel trim > 0.8and Average of long term fuel trim > 1.24 |
Diagnosis Time | ? Contineous |
MIL On Condition | ? 2 Driving Cycles |