Circuit Description
WARNING: This page is about a different car, the 2002 Toyota MR2. 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 P0174 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
- Air induction system malfunction.
- Fuel injector is restricted.
- Defective Mass Airflow (MAF) meter.
- Defective Engine Coolant Temperature (ECT) sensor.
- Improper fuel pressure.
- Exhaust system leak.
- Heated oxygen sensor circuit is open or shorted.
- Defective heated oxygen sensor (bank No. 1 sensor No. 1 or bank No. 2 sensor No. 1).
- Defective ECM.
- Vehicle ran out of fuel.
DTC P0172 and/or P0175 is set when fuel trim is driven lean beyond a certain value. Possible causes are:
- Fuel injector is restricted or leaking.
- Defective Mass Airflow (MAF) meter.
- Defective Engine Coolant Temperature (ECT) sensor.
- Ignition system malfunction.
- Improper fuel pressure.
- Exhaust system leak.
- Heated oxygen sensor circuit is open or shorted.
- Defective heated oxygen sensor (bank No. 1 sensor No. 1 or bank No. 2 sensor No. 1).
- Defective ECM.
- Vehicle ran out of fuel.