Diagnostic Aids

Inspect for the following conditions:

1. The PCM will not enable the catalyst test until the following conditions are met:
   • The engine speed is plus or minus 265 RPM from the desired idle.
   • The Throttle Position (TP) is 1.5 percent or less.
   • The short term FT is between -20 and 20 percent.
2. The catalyst test will abort if the vehicle falls outside the conditions listed above while the test is running.
NOTE: When you use the scan tool to force the cooling fans ON, use the next list and previous list soft keys in order to enter the catalyst data list. If the catalyst data list is not entered this way, the cooling fan control will be canceled.
3. The catalyst test may abort due to a change in engine load (i.e., A/C, coolant fan). If this problem occurs, use the scan tool to force the cooling fans ON then return to step  3 under DIAGNOSTIC PROCEDURES.
4. The number of attempted tests is limited to 18 per key cycle.
5. More than 6 tests may have to be attempted in order to get 6 completed tests. An aborted test counts as an attempted test.
6. If 18 tests have been attempted, and a decision has not been made this key cycle, turn the key OFF for 30 seconds, start the vehicle, and perform the Conditions for Running DTC, including the 10 minute run time.
7. After returning to an idle, the HO2S 1 signal may stay rich or lean for several seconds, causing the test to be delayed.

If the condition is determined to be intermittent, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.