P0171

DTC P0171 Fuel Trim Malfunction - System Too Lean (Bank 1)

DESCRIPTION
The air/fuel control system, in addition to a number of sensors, includes the following components and Systems
- Intake air system.
- Exhaust system.
- Evaporative emissions control system (includes purge control solenoid valve).
- Fuel injectors.
- Fuel pressure regulator.
- Fuel pump.

For the air/fuel ratio to be within limits, all of the sensors, components and systems associated with the air/fuel control system must function within normal parameters.

FAILURE CONDITIONS
(FOR SHORT-TERM FUEL TRIM)
The ECM will set a code and the Malfunction Indicator Lamp (MIL) will turn on if the short-term fuel trim value goes 10% to 15% rich [for P0172] or if the short-term fuel trim additive value is less than 0.4 milliseconds, or 10% to 15% lean [for P0171] for 30 seconds during two driving cycles when the following conditions are met
1. ECM is in closed loop operation.
2. Engine speed is below 1000 RPM.
3. Engine coolant temperature is above 158 °F (70 °C).
4. Canister purge system is not operating
5. Mass air flow is less than 7.5 g/s [for P0172] or 5.5 g/s [for P0171].

(FOR LONG-TERM FUEL TRIM)
The ECM will set a code and the Malfunction Indicator Lamp (MIL) will turn on if the long-term multiplicative value is less than 77% for 30 seconds [for P0172] or if the long- term fuel trim value goes to 10% to 15% lean [for P0171] for 30 seconds during two driving cycles when the following conditions are met
1. Engine load exceeds 1.8 milliseconds.
2. ECM is in closed loop operation.
3. Engine coolant temperature is above 158 °F (70 °C).
4. Canister purge system is not operating
5. Mass air flow is less than or 5.5 g/s.
6. Engine speed is below 1000 RPM.

Test Procedure Part 1:

Test Procedure Part 2: