P0171

DTC P0171 SYSTEM TOO LEAN (BANK 1)

1. OUTLINE OF DIAGNOSIS
Detect fuel system malfunction by the amount of main feedback control.

Diagnostic method
Fuel system is diagnosed by comparing the target air fuel ratio calculated by ECM with the actual air fuel ratio measured by sensor.




2. ENABLE CONDITIONS

3. GENERAL DRIVING CYCLE
Perform the diagnosis continuously at idling or at a constant speed after warming up the engine.

4. DIAGNOSTIC METHOD




Abnormality Judgment
Compare the diagnosed value (fsobd) with the threshold value, and if a condition where the malfunction criteria are met continues for more than 50 seconds, judge that there is a fault in the fuel system.




Normality Judgment
Judge as OK when the malfunction criteria are completed for 10 seconds or more.

5. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed

6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITIONS
- When similar driving conditions are repeated 3 times and the result is OK.
- When "Clear Memory" is performed

7. FAIL SAFE
None

8. ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)