California Models

Data Trouble Code No. 25 - Air-Fuel Ratio Lean Malfunction

Detecting Condition

Main Heated Oxygen Sensor voltage is 0.45 volts or less (lean) for 90 seconds under the following conditions (2 trip detection);

- Engine coolant temperature 70°C (161°F) or more.
- Engine speed 1,500 rpm or more.
or
Engine speed varies by more than 15 rpm over the preceding crankshaft position during a period of 20 seconds or more under the following conditions (2 trip detection);

- Engine speed idling.
- Engine coolant temperature between 60°C (140°F) and 95°C (203°F).
or
Difference of air/fuel ratio feedback compensation value between front (no. 1 - 3 cylinders) and rear (no. 4 - 6 cylinders) is more than 15 percentage for 20 seconds or more under the following conditions (2 trip detection);

- Engine speed: 2,000 rpm or more.
- Engine coolant temperature between 60°C (140°F) and 95°C (203°F).

Trouble Area

- Open or short in Main Heated Oxygen Sensor circuit.
- Main Heated Oxygen Sensor.
- Ignition system.
- Engine Control Module.
or
- Open or short in Injector circuit.
- Fuel line pressure (leak or blockage).
- Mechanical system malfunction (timing belt skipped).
- Ignition system
- Compression pressure.
- Volume Air Flow Meter.
- Engine Control Module.

Malfunction Indicator Lamp

Normal Mode On
Test Mode On