P0171

DTC P0171 SYSTEM TOO LEAN (BANK 1)




1. OUTLINE OF DIAGNOSIS
Detect the 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 CONDITION
Map 5

3. GENERAL DRIVING CYCLE
Perform the diagnosis continuously at engine idle or constant vehicle speed after warm-up.

4. DIAGNOSTIC METHOD




^ Abnormality Judgment
Judge that the fuel system malfunction occurs when the time during completing the malfunction criteria below continues 50 seconds or more by comparing the diagnosed value (fsobd) with threshold value.




^ Normality Judgment
Judge OK when the malfunction criteria below are continued for 10 seconds.

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

6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
^ When OK with similar drive in 3 driving cycles.
^ When "Clear Memory" was performed

7. FAIL SAFE
Rich side malfunction
^ Purge control solenoid valve control: Not allowed to purge.
^ Heavy fuel judgment control: Not allowed to carry out the heavy judgment.

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