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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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99 chevy tahoe: 5.7L in my bay with a p0442 small evap leak..gas cap

Customer Question

I have a 99 chevy tahoe 5.7L in my bay with a P0442 small evap leak. gas cap tests fine. I have pressurized the system, system holds pressure, i have also smoked the system. still no evidence of leak. started vehicle, sealed vent and opened purge to put system under vac. and monitered the tank pressure with snapon solus scanner. vac does decay about 0.50 mmHg per minuet. according to service info any decay in 15sec will set code. do i have a significant leak, how can i pinpoint the location of leak if it is so small and only under vac? or could it be a sensor, or pcm?
Submitted: 7 years ago.
Category: Chevy
Expert:  Gentry314 replied 7 years ago.
When you cleared code did it come right back?
Customer: replied 7 years ago.
yes with in 3 days

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