 Earl Glant shot foreman here at Township Chevrolet for another edition of Tech Talk Today we're going to talk about check engine lights and more specifically your evap system causing that check engine light on everyone's got a friend or a famous member or maybe it's you that's driving around One of your vehicles at home has that check engine light on You've taken it somewhere and they've said oh don't worry about that It's just an evap concern and it won't cause any drivability problems and won't cause any issues down the road So you just kind of put up with that light there some people even take it a step farther and put that little piece of the Black electrical tape over it and so today I'm just gonna give you a quick rundown on what the evap system is Kind of how it functions Maybe some reasons why you might want to think about getting that light off and your dash and getting that repair done so evap system is there to Absorb or to take care of or deal with the fumes in the gas tank. So years and years ago Before evap systems come around used to walk through a parking lot in a hot day And you kind of see the fuel vapors rising out of the out of the gas caps or gas tank filler area on vehicles So that systems there so as the temperature changes and you have the fumes come off the gas tank It stores it in the part of the evap system called the charcoal canister So that's basically just a little holding tank that stores those fumes until it can be burnt in the engine And the way the system works is kind of basics of it and pretty much all manufacturers do the same thing When you're driving down the road and it's meet it's met certain conditions So the ambient temperature outside is a certain temperature. You've got your engine at a certain temperature You're usually the rule of thumb is over a quarter tank or under the three quarter mark So in between there Once the computer sees that criteria is met then it'll open up a purge valve The purge valve is located most of the times on the engine and that uses the engine vacuum to draw those fumes out of the gas tank The one and the charcoal canister that that's been stored there and actually burn them through the tailpipe and burn them up So they're not just escaping into the atmosphere To do that it also needs a vent valve in the system the vent valve is there You can just like a just like a kid drinking a juice box if you're sucking up The juice out of the juice box the juice box tries to kind of go in on itself So what they do is they put a vent valve on that so as it's pulling the fumes out of the tank and the charcoal canister It's also drawing in fresh air behind it so that it doesn't have that suction effect So the main system the main parts of the system are your computer that Controls the system you've got your wiring obviously and you've got your your piping that goes from the Fuel tank and charcoal canister and your vent to your purge to your engine and you've got your vent valve your purge valve and your charcoal canister so Which leads me to the next thing the most expensive part to fix on that system is your charcoal canister Your charcoal canister in theory will pretty much last forever or should last the life of your vehicle what will shorten the life of your charcoal canister is If you're one of those people that are constantly, you know getting squeezing that extra few cents out of the fuel pump and filling up your gas tank You're gonna round up to the nearest dollar We don't recommend that The vent for that system for the fresh air to pull the fresh air in from your vent valve Is usually located around the filler neck somewhere So what'll happen is when you're running the fuel up the fuel actually overspill before it comes out of you know Obviously down to the ground it'll overfill into that charcoal canister raw fuel Will will damage that canister and cause all kinds of evap issue So your best bet is no matter how close you are to that dollar amount. Just let it shut off so having said that the charcoal canister normally is not an issue usually it's You've got a vent valve or purge valve issue Rarely you can have a line that's broke or an air leak in the line somewhere that can cause that light to come on Another thing is to obviously gas caps not being tightened if you if you have a car that has a gas cap You can usually read on the cap It'll say two clicks to tighten and that's to seat that valve in there properly So that you don't end up having to like come on for a small leak in the evap for a medium leak or large leak Or an evap system fault code So you want to make sure that's tight all the way and then with a lot of the newer cars with the cap Capless fuel system where there is no fuel cap You want to make sure if you're you're fueling your car up and you're seeing a bunch of ice and snow around Don't just you know shove the nozzle in there and start fueling just clean that snow off because the flap that you're sticking the The nozzle into that's actually not the one that does the ceiling there's actually one further down But when you open that up sometimes you'll get some water or ice will fall down in there Of course it can melt when it gets warmer and freeze up again and hang that hang that little Valve open or flap open there and cause that light to come on so It doesn't normally cause any drivability issues anything around with your evap That is true. The only downside of the whole deal is if you have another fault in your vehicle somewhere Emissions related fault. You've got no idea That it's happening. So with your check engine laid on all the time You're not going to know unless there's a drivability issue. So It's always good to have that light off and most of the time It's it's not a real difficult system to diagnose if the shop You're thinking if he was got the proper equipment and we have it here And you get the knowledge to fix it. So If you got that light on and you're tired of seeing that little yellow thing lit up in your dash And you've been told by somebody else. It's an evap problem. You think it might be Bring it on into us and we'll put our scan tool on and give you an idea what it's going to cost to get that light out That's been another edition of tech talk today. We're all glad here township Looking forward to do business with you and once again if you guys have any Comments or anything you have on your own car that you might want to kind of a rundown on how things work or Any systems on a car just drop it in the comments below in the video and we'll do our best to get that on there Thanks again