P0171

DTC P0171 - SYSTEM TOO LEAN (BANK 1)

OUTLINE OF DIAGNOSIS




Detect the malfunction of fuel system by the amount of main feedback control.

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







ENABLE CONDITION

GENERAL DRIVING CYCLE
Perform the serial diagnoses with idling or a constant vehicle speed after engine starting.

DIAGNOSTIC METHOD




Judge that the malfunction occurred in fuel system when the malfunction criteria are completed for 50 seconds or more by comparing the diagnostic value (fsobd) with threshold value.




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

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

MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When diagnosed OK with the similar driving for 3 driving cycles in a row
- When "Clear Memory" was performed

FAIL SAFE
None

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