How to Fix a Check Engine Light

Oh no, the “check engine” light stays on when you start the car, or it just winked on while you were driving!  Here’s the super easy fix.

Remove the Fuel Filler Cap

Remove the fuel filler cap – the gas cap. Open it as if you were going to put gas in the car, and then close it. Make sure you screw it on correctly, so that it’s easy to turn, and makes a confident “click  when it’s in all the way.

Drive to Reset the Check Engine Light

Drive the car for a while. The light should go out all by itself. If you don’t drive much, it may take a day or two.

What the Check Engine Light Means

In the vast majority of cars, the check engine light indicates a malfunction in the emission control system. When it’s on, your car is still running fine, but is making more pollution than it should.

Replacing the gas cap works about 90% of the time. The fuel system is slightly pressurized. If the gas cap is on cockeyed, the pressure can’t build, and the light is turned on.

If removing and replacing the cap doesn’t work, try it again.  If it still doesn’t go out, you need to take it to your mechanic, because there is something wrong with your emission system.

The emission system is made up of a number of sensors and air valves. The most expensive part in your emission system is the catalytic converter.  

Be wary of the mechanic who says he needs to replace that (they may call it the cat converter, or just the converter, or just the cat) first. You can drive the car to a different mechanic – a good dealer will usually you give you a straight answer.

If any other panel lights (except the low fuel, seatbelt, and door ajar) stay on with the check engine light, the car is telling you there is something mechanically wrong with the engine. Drive it to the nearest mechanic.

If it’s making an odd noise, or smoking shut it off right now and have it towed.

Please Note: Do not use this procedure if you are not certain that you can complete it safely, or if it does not seem accurate. Skippity Whistles provides this information as advice, and cannot accept any liability from your usage of it.


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Published by John D Reinhart

Author, technical writer, videographer, actor, and naval historian John D Reinhart is a very busy guy. You can find his novels as

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