I have driven my 2009 prius 17000 miles in 14 months with no issues that have triggered "check eng" light (MIL). To test the functionality of that part of the engine management computer that monitors for faults, I removed the fuel filler cap and drove 118 miles with several stops and restarts with no MIL. My two previous cars, 1999 chev metro and 2007 nissan versa, would show a MIL with this test. When ignition on but before "ready" light, all of the warning lights are on including the MIL. Can anyone think of another test that I can do to satisfy myself on this matter or should I not persue this issue. >>>>Tortus
Here's a test you can easily perform: disconnect a wiring harness connector that connects to a spark plug igniter. The engine should run very rough on 3 cylinders, and that should prompt the check engine light to come on.
OBD-II systems are required to have a power mode that does a "lamp test" of various things, notably including the MIL, to make sure the *lamp* is working before any emissions tests are done. In the Prius, that mode is IG-ON that you get by *not* pressing the brake and toggling the power button two times to get all the dash lights to go on. Upon pressing the brake and hitting the button again it should go to READY [equivalent of starting the engine in conventional cars] and the MIL should go out, unless there's a problem. . Almost exactly equivalent to standard inspection procedure. . If you want to actually force an error, there are numerous ways to do it. Another really easy one is to disconnect the mass-airflow connector on the front of the air-box; the ECM should signal an immediate problem. . _H*
