Heated Oxygen Sensor Monitor

This monitor applies to DTCs P0133 and P0139. Following conditions must be met during the test:

• Engine coolant temperature must be 176°F (80°C) or more.
• Atmospheric temperature is 14°F (-10°C) or more.
• Selector lever is in "D" range.

Monitor takes about 5 minutes to complete. This cycle must be completed 2 times. Run monitor as shown. See Fig 1. Perform steps as follows:

1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
2. Start engine and accelerate to 35-40 MPH.
3. While keeping accelerator pedal position constant, keep speed at 35-40 MPH (4th gear on M/T) for 120 seconds or more (this is when monitor runs).
4. Return vehicle to shop and Turn the ignition switch to LOCK position. Recheck for DTCs. If DTC P0133 or P0139 resets, return to appropriate repair procedure under DIAGNOSTIC TESTS .

Fig 1: Running Heated Oxygen Sensor Monitor

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.