General Description
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.
DTC Description
Checking the fuel trime value at idle under detecting condition, if its average exceeds the limit over certain period, ECM sets P2189.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
DTC Strategy | Additive Long Term FT upper limit reached
| Air leakage Improper fuel pressure PCV valve stuck Clogging of injector |
Enable Conditions | 5.8% < torque < 23%
Engine speed > 500rpm
ECT > 65.3?(149.54?)
IAT < 80?(176?)
Fuel System Status Closed loop
|
Threshold value | Long Term FT (additive) > 5.53%
|
Diagnosis Time | 8 sec
|
MIL On Condition | 2 Driving Cycles
|