Loose gas cap causing "check engine" light to come on?

(2012-02-04 15:20:15)

1. KERPLUNK Says: I have a 2004 Chevy Malibu and I was at Autozone today where I had my car hooked up to the little computer code reader and was told my CE light was coming on due to a loose gas cap and it's like $8 - $10 for a new gas cap. Questions:

1) How is this a problematic issue for my car itself to have a loose gas cap (like does that mean I'm not getting the maximized amount of gas for what I pump into my car)?

2) How long can I delay getting a new gas cap?

3) Will my car go through some sort of performance decline as a result of not making it a huge priority to get a new one?

2. Michael Says: The "evap" code that showed up is just saying the fuel system has a vapor leak large enough to release unwanted vapors into the air. As the car owner/driver you would never have noticed the difference, which is why the light came on - to tell you the emissions are not right.

The evap code is not even specific for the gas cap. Any sort of leak in the upper part of the fuel system - the vapor recovery part - will produce the same code. The gas cap is just the most common fault and the cheapest to deal with. The usual approach is to drive for a month or two, being sure to tighten the gas cap when you get gas (most caps of your car's era click when tightened - tighten at least three clicks) and perhaps putting petroleum jelly (never silicone lubricant!) on the rubber seal of the gas cap. If the light persists replacing the gas cap is the next step. If that doesn't do it things get tougher - a shop will do a smoke test, putting pressurized smoke in the tank and looking to see where it is escaping.

The problem is not likely to get worse or affect your driving or fuel economy, just the car's emissions.

3. deviousone Says: 1st. The fuel system thats on your car has a vapor canster that a purge valve solonoid when engine is frist started starts to pump the vapors from the tank to the vapor canister where a different vacuum hose takes the fuel vapors to the throttle body to be burn as fuel. If the tank is unable to pressurise due to faulty gas cap, yes you could experince engine runability issues. 2nd. I would of replaced it the day i was told it was bad. 3rd. Again, runability problems slightly noticed at frist. After a while you will notice gas mileage drops, cat converter may go bad, ect. REPLACE IT ASAP, LIKE IN THE MORNING.

4. Eric Says: it could be on because your gas cap was loose; tighten it and turn your car off for a min and turn it back on, or turn you car off and dissconnect the battery for about 2 min then hook it back up and see if the light is still on

if it is then just spend the $10 on an new gas cap

5. rhymes with orange Says: Older cars just had a vent in the cap to release gas fumes into the air. New EPA standards require your cap to seal the fuel vapors from escaping. Air is pumped into your tank and fumes are routed up to the engine to be burned

6. chandan Says: depending upon whether your vehicle has an in tank pump unit it does effect performance due to entry of air in the tank leading to vaporisation
u better change the cap and recheck for codes

7. Ramon C Says: I have to read between the lines in your statement. Are you saying you cannot afford this 8 dollars to buy a new gas cap or are you saying you choose not to believe the diagnosis by the Autozone people? If this minor cost is not affordable I have to wonder what else is wrong with your car that you have chosen to ignore like worn tires or brakes, burned out lights, worn windshield wipers, etc. People have two primary reasons not to take proper care of their cars. Ignorance and not enough dollars. Either reason leads to car breakdowns and crashes. According to AAA the number one reason for assistance on the road is people running out of fuel. Imagine that! Sure you can drive the car like this. Gasoline vapors will vent into the atmosphere rather than be cycled thru the engine to be burned and you cost per mile will increase. So rather than pay for the gas cap you will pay at the pump. Since fuel is needed all the time it will take just a couple of fillups to cost you more than the 8 bucks for the gas cap. Your money, your choice.