Trip

The ability for a diagnostic test to run depends largely upon whether or not a trip has been completed. A trip for a particular diagnostic is defined as a key ON and key OFF cycle in which all the enabling criteria for a given diagnostic has been met allowing the diagnostic to run vehicle operation, followed by an engine OFF period of duration and driving mode such that any particular diagnostic test has had sufficient time to complete at least once. The requirements for trips vary as they may involve items of an unrelated nature, such as driving style, length of trip, ambient temperature, etc. Some diagnostic tests run only once per trip, such as the catalyst monitor, while others run continuously, such as the misfire and fuel system monitors. If the proper enabling conditions are not met during that ignition cycle, the tests may not be complete or the test may not have run.