Circuit Description
WARNING: This page is about a different car, the 2002 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
Fuel trim refers to feedback compensation value compared against basic injection time. Fuel trim includes short-term and long-term fuel trim.
DTC P0171 and/or DTC P0174 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
- Air induction system malfunction.
- Fuel injector malfunction.
- Defective Mass Airflow (MAF) meter.
- Defective Engine Coolant Temperature (ECT) sensor.
- Improper fuel pressure.
- Exhaust system leak.
- Air/Fuel (A/F) sensor circuit is open or shorted.
- Defective Air/Fuel (A/F) sensor.
- Vehicle is ran out of fuel.
- Defective ECM.
DTC P0172 and/or DTC P0175 is set when fuel trim is driven lean beyond a certain value. Possible causes are:
- Fuel injector malfunction.
- Defective Mass Airflow (MAF) meter.
- Defective Engine Coolant Temperature (ECT) sensor.
- Improper fuel pressure.
- Exhaust system leak.
- Air/Fuel (A/F) sensor circuit is open or shorted.
- Defective Air/Fuel (A/F) sensor.
- Defective ECM.