Diagnostic Aids

Inspect for the following conditions:

• The PCM will NOT enable the catalyst test until following conditions are met:
  1. The engine speed is plus or minus 150 RPM from the desired idle.
  2. The Throttle Position (TP) is less than 0.5 percent.
  3. The short term integrator is between -20 to +20 percent.
• The catalyst test will ABORT if the vehicle falls outside the conditions listed below while the test is running:
  1. The engine speed is plus or minus 150 RPM from the desired idle.
  2. The Throttle Position (TP) is less than 0.5 percent.
  3. The short term integrator is between -20 to +20 percent.
NOTE: When using the scan tool in order to force the cooling fans ON, use the next list and use the 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.
• The catalyst test may abort due to a change in engine load due to the A/C, the coolant fan, or other components. If this condition occurs, use the scan tool in order to force the cooling fans on. Return to step 3 in diagnostic procedures, then repeat the test.
• The number of attempted tests is limited to 18 per key cycle.
• You may need to attempt more than 6 tests in order to complete 6 tests. An aborted test counts as an attempted test.
• If 18 tests have been attempted, and if a decision has not been made during this key cycle, turn OFF the key for 30 seconds. Start the engine, and perform the Conditions for Running DTC, including the 10-minute run time.
• 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 intermittent, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.