1999 Toyota Corolla Q&A
1999 Toyota Corolla Question: 1999 Toyota Corolla, "CATALYST MON INC"
When a monitor doesn't complete it could be because the conditions to run the test weren't reached, or it could be blocked or delayed for some reason. Code enable criteria is often a good clue for any possible blocking conditions. If the fuel trims are not within a specific range, or if there is a trouble code pending for an O2 sensor or for the fuel system then the engineers often feel that the catalyst test wouldn't be reliable so it gets suspended or blocked. So look at ambient temperature limits, coolant temperature limits, (sometimes a stuck open thermostat suspends the test) and monitor them in scan data while performing the "drive cycle" which is a published routine that should see each of the tests run in succession. BTW how many monitors are incomplete at this time, and how many are permitted to be incomplete? Here in Pa your 1999 could still have two incomplete and pass, in 2000 we went to one. - cardocIII