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%.
This DTC is set if long-term and short-term value are lower than the standard value.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● A/F learnt value(KLRN) & intergral value of A/F feedback compensation(KI) are monitored | ● Poor connection ● Air cleaner blockage ● Defective injector ● Improper fuel line pressure ● Defective ECM |
Enable Conditions | ● Closed loop | |
Threshold value | ● KLRN < -12.5%, KI < -7% ● Idle - (KLRN+KI) < -17% | |
Diagnostic Time | ● Continuous | |
MIL ON condition | ● 2 driving cycles |
