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Toolhut, ASE Certified Technician
Category: GMC
Satisfied Customers: 515
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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I'm having problems with the evap monitor not being ready

Customer Question

I'm having problems with the evap monitor not being ready for emissions testing. The others are fine. I've driven about 300 miles - city and freeway with no success.
Submitted: 1 year ago.
Category: GMC
Expert:  Toolhut replied 1 year ago.

Hi, My Name is***** have over 20 years experience repairing vehicles. I am a ASE Certified Master Auto Technician. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.I also try to give all of the information you may need expecting a positive rating. If there is any reason I cannot get a positive rating please let me know.

There are several criteria for the vehicle to run the monitor. The fuel tank must be between 1/4 and 3/4 full and set for 8 hours prior to being driven then it must be driven 45-55MPH for 20 minutes. If it sees any criteria not met it will not run the monitor.

Customer: replied 1 year ago.
Does the 45-55 mph drive matter if it includes traffic light stops etc?
Expert:  Toolhut replied 1 year ago.

yes it has to be continuous. no stopping

Customer: replied 1 year ago.
I tried filling the tank to 1/2 full. Left vehicle parked overnight (11 hours). This morning drove for 25 min twice keeping speed close to 50mph (used cruise control). My reader still shows the Evap Monitor is INC. Others are ok. No codes.
Expert:  Toolhut replied 1 year ago.

I would have to see some scan data. It obviously is seeing a leak or the fuel tank pressure is not sufficient for the test.