Fuel Trim Monitor

This monitor applies to DTCs P0171 and P0172. Following conditions must be met during the test:

• Engine coolant temperature is 176-207°F (80-97°C).
• Atmospheric temperature is 14-140°F (-10-60°C).
• Selector lever is in "D" range.

Monitor takes about 35 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 55-60 MPH.
3. Drive at 55-60 MPH for 30 minutes or more (5th gear on M/T). During this period DO NOT drive at constant speed for more than 120 seconds. Carry out gradual deceleration and acceleration within every 120 second time frame.
4. Return vehicle to shop and Turn the ignition switch to LOCK position. Recheck for DTCs. If DTC P0171 or P0172 resets, return to appropriate repair procedure under DIAGNOSTIC TESTS .

Fig 1: Running Fuel Trim Monitor

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.