Subaru Crosstrek Service Manual: Dtc p0171 system too lean bank 1
ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)
DTC P0171 SYSTEM TOO LEAN BANK 1
Refer to DTC P0172 for diagnostic procedure. Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0172 SYSTEM TOO RICH 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. EXECUTION CONDITION
Secondary parameters | Execution condition |
Main feedback | In operation |
3. GENERAL DRIVING CYCLE
Perform the diagnosis continuously at idling or at a constant speed after warming up the engine.
4. DIAGNOSTIC METHOD
Compare the diagnostic value with the threshold value, and if a condition meeting the malfunction criteria listed below continues for 10 s ? 3 time(s) or more, judge that there is a fault in the fuel system.
Malfunction Criteria | Threshold Value |
Offset amount of main feedback compensation | ≥ Value from Map |
Amount of air g/s (oz/s) | 0 (0) | 3.2 (0.11) | 6.4 (0.23) | 9.6 (0.34) | 12.8 (0.45) | 16 (0.56) | 19.2 (0.68) |
Threshold Value | 1.33 | 1.33 | 1.33 | 1.33 | 1.33 | 1.33 | 1.33 |
Time needed for diagnosis: 10 s ? 3 time(s)
Malfunction indicator light illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
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