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.
If the revised air-fuel-ratio at idle is higher than specified value, ECM recognizes it as a fault and sends P2187.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Check the revised air-fuel-ratio at idle | 1. Air leakage 2. Improper fuel pressure 3. PCV valve stuck 4. Clogging of injector |
Enable Conditions |
•
Coolant temperature > 80.3℃
•
Intake air temperature < 80.3℃
•
Throttle angle < 60%
•
Lambda feed back control condition - active
•
Purge valve control duty = 0%
•
No MAP sensor error
•
No purge valve error
•
No WTS error
•
Engine speed ≤ 920rpm
•
Air mass ≤ 24kg/h | |
Threshold Value |
•
Air mass correction value of additive fuel adaption range > 2.9 kg/h | |
Diagnostic Time |
•
10 sec | |
MIL ON Condition |
•
3 Driving Cycles |
