Hopefully something here will be useful

2005 Prius check engine light

I posted the previous entry in preparation for this one. While driving home from work last week my "check engine" light came on. I brought my car in to Cherry Hill Toyota as the manual said to bring the car in in response to this light. Beforehand I was hoping to extract the error codes by placing the car into diagnostic mode, but apparently the diagnostic mode doesn't give you access to the OBDII error codes which are what you really need. Toyota told me that the particular error they extracted is due to the emissions test failing. One common source of automobile emissions is a loose or nonexistant gas cap which causes gasoline to evaporate. As part of being a PZEV (Partial Zero Emissions Vehicle) it tests any emissions coming from the gas cap area. Apparently when it detects the cap is loose and gasoline vapor is escaping it triggers the "check engine" light. For something so obvious and easily resolved Toyota really should have had it trigger a message on the multi-function display screen, but alas they didnt. So the Toyota tech tightened the gas cap and cleared the error from the computer. PLEASE NOTE: Just tightening the gas cap DOES NOT cause the "check engine" light to go out. According to Toyota the light wont go out until the computer performs another emissions test. According to Paul Schreiber at http://paulschreiber.com/blog/2005/05/10/my-prius-check-engine-light you "have to drive the car for at least 20 minutes 2-4 times for the car to believe the gas cap really is fixed."

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