Preliminary Checks

1. Be sure that all TSB's pertaining to Self Test Codes 171, 173 and 179 have been performed.

2. Check to see that all Powertrain Control/Emission Diagnosis Service Manual steps have been taken and no causes for codes 171, 173 and/or 179 are found.

3. See if data given on the Customer Information Worksheet indicates that the vehicle has been driven at altitudes greater than 5000 ft. (1525 meters) or at ambients greater than 100 degrees F (38 degrees C).