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.
ECM assumes Lambda sensor is out of control and shows P2195 when upstream O2 sensor displays lean condition in spite of continuous correcting by downstream O2 sensor.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Check the revised air-fuel-ratio | 1. Poor connection 2. S1 3. Blocking of intake system 4. Fuel leakage in injector 5. Improper fuel pressure |
Enable Conditions |
•
Engine speed 1120~3000rpm
•
Catalyst temp.(model) ＞350℃ | |
Threshold Value |
•
Deviation value of air fuel ratio control > 0.07 | |
Diagnostic Time |
•
- | |
MIL ON Condition |
•
3 Driving Cycles |
