# EVAP Monitor Ready, Yet CEL is on for EVAP problem **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** hyundai, sonata\ **Created:** [September 29, 2016, 6:50am UTC](https://community.cartalk.com/t/evap-monitor-ready-yet-cel-is-on-for-evap-problem/95887 "2016-09-29T06:50:34Z")\ **Posts on this page:** 1\ **Showing post:** 7
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [September 30, 2016, 1:30am UTC](https://community.cartalk.com/t/evap-monitor-ready-yet-cel-is-on-for-evap-problem/95887/7 "2016-09-30T01:30:27Z")
@Tester (one of the experts who post here regularly) recently posted a good overview diagram of how evap systems are configured. I hope you can see it OP by clicking on the link below. > [@Having troubles starting my car, mostly after pumping gas!](https://community.cartalk.com/t/having-troubles-starting-my-car-mostly-after-pumping-gas/95831/8): > > The problem might be with the purge valve in the EVAP system. This valve is normally closed. But if the valve sticks open, fuel vapors can be forced into the engine while refueling, and this can cause a flooded condition where it requires that the accelerator be depressed in order to start the engine. Since the advent of OBDII, it’s impossible to flood the carbon canister in the EVAP system on today’s vehicles. Because not only does it have roll-over valve, it also has a refueling control valv… Taking a look at Tester’s diagram, you can see there’s lots of places for an evap leak to occur. The purge valve is a common one, it gets stuck on sometimes, but it sounds like you’re sure you’ve eliminated that as the source of the leak. So you now have to just go through all the other possibilities one by one. If you could find it like you’d find a leak in a tire – putting it underwater and looking for bubbles – that would definitely make it simpler, but alas, you can’t do it that way with a car. Shops have a sort of similar way as the under-water method to find an evap leak fast, a machine that injects smoke into the top of the gas tank. Then they just look around for where the smoke is getting out. If no smoke is getting out, but the computer says there is a leak, then the next suspect is the pressure (or vacuum) sensor may be bad. So one idea, ask a shop to do a smoke test. They’ll tell you what they find, then you can decide if you want to fix it yourself or let them do it. --- _[View the full topic](https://community.cartalk.com/t/evap-monitor-ready-yet-cel-is-on-for-evap-problem/95887)._