Circuit Description

Fuel trim refers to feedback compensation value compared against basic injection time. Fuel trim includes short-term and long-term fuel trim. DTC P0171 is set when fuel trim is rich beyond a certain value. Possible causes are:

• Air intake hose loose.
• Fuel line pressure.
• Injector blockage.
• Heated oxygen sensor.
• Mass Airflow (MAF) sensor.
• Engine Coolant Temperature (ECT) sensor.

DTC P0172 is set when fuel trim is lean beyond a certain value. Possible causes are:

• Fuel line pressure.
• Injector blockage or leak.
• Heated oxygen sensor.
• Mass Airflow (MAF) sensor.
• Engine Coolant Temperature (ECT) sensor.