Readiness Drive Cycle Test
After all repairs have been made, any trouble codes have been erased and the MIL has been turned off, you will need to perform a Readiness Drive Cycle Test before any emissions tests can be properly done. OBD II systems conduct self-diagnostic system tests under certain conditions or enabling criteria, as listed below.
- Elapsed time since vehicle engine start up
- Engine temperature
- Throttle position
- Engine speed
- Vehicle speed
Most of the various systems tests, conducted by the different monitors, are only done after the engine has reached normal operating temperature.
The computer runs three types of tests:
- Passive Tests -- These are the tests that monitor a system or component without affecting its operation.
- Active Tests -- Where the computer has the monitor produce a test signal so that it's response can be checked against stored information.
- Intrusive Tests -- Where the computer performs system checks that directly affect vehicle performance and emissions.
After a passive test is run and a failure is detected, the computer then performs an active test procedure on the system. If, after the active test, another failure is detected the computer will run an intrusive test. If after the intrusive test another failure is confirmed, the computer may not, at this time, store a trouble code and/or illuminate the MIL until after this same failure occurs after two consecutive test series are completed. Because of this characteristic, it is suggested that you perform the following I/M.
Readiness Drive Cycle Test TWICE to be sure that all sub-systems have been checked, flags are set and all I/M monitors are in the ready condition. It is important that these benchmarks or messages the OBD II system uses indicate that all emission monitors have been run before the vehicle is released to the consumer or goes through an I/M 240 test.
Click here to go back to About Catalytic Converters.