In order to provide the best possible combination of drivability, fuel economy and emission control, the ECM uses a closed loop air/fuel metering system. The ECM 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 ECM 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 ECM 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.
Checking the fuel trime value at idle under detecting condition, if its average exceeds the limit over certain period, ECM sets P2187.
MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycles.
Item | Detecting Condition | Possible cause |
DTC Strategy |
•
Monitor the fuel trim value at idle | 1. Air leakage 2. Improper fuel pressure 3. PCV valve stuck 4. Clogging of injector |
Enable Conditions |
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Engine warm-up sufficiently
•
Engine running under Idle state over 5 minutes
•
60℃(140℉) ≤ Engine coolant temperature ≤ 115℃(239℉)
•
No disabling faults (DTCs related to HO2S, purge valve,catalyst ) | |
Threshold value |
•
Average of short term fuel trim > 0.8 and Average of long term fuel trim > 1.24 | |
Diagnosis Time |
•
Continuous | |
MIL On Condition |
•
2 Driving Cycles |
