Q: gas light loose and check engine light comes on I replaced gas cap and the issue still happens

asked by on

It says gas cap loose and check engine light comes on I replaced gas cap and it still is the same what could it be.

My car has 167000 miles.
My car has an automatic transmission.

The gas cap is the most common source of evaporative emissions, which would be a reason the check engine light would come on. The evaporative emissions system is designed to limit the evaporation of fumes from the fuel in your fuel tank. We all know how easy it is to forget our gas caps at the gas station or simply not tighten it tight enough. This is the reason for the gas cap loose illumination. It often saves customers an unneeded trip to a shop for a gas cap.

Your evaporative emissions system consists of the fuel tank, vapor canister, several pressure sensors, valves and many feet of hoses running from the motor to the fuel tank. If there is a leak in any part of this system, the check engine light will turn on. At this point you need to read the code with a scanner and follow the diagnostic flow chart for that code.

It is often necessary to connect a smoke machine to the emissions system to locate the leak. Smoke machines are not cheap, so most people won’t be investing in one to diagnose their vehicle. There really isn’t another good technique to find a leak in an evap. system. You can do a visual inspection, but this will only reveal a problem if the leak is very large. The code will let you know if it is a large or small evaporative emissions leak.

If you wish to have an experienced technician to help you diagnose this, a certified YourMechanic technician can be dispatched to your location to inspect your vehicle’s check engine light and diagnose any repairs necessary.

Good luck!

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. gas light loose and check engine light comes on I replaced gas cap and the issue still happens

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Q: My car will crank but will not start.

Thanks for writing in about your 1994 Buick Roadmaster. There are many things that can cause a no start condition. You may want to have this thoroughly looked at in person by a professional before moving forward with any other...

Q: need to know how to change a coolant bypass solenoid and where it is located. Can't find anything on the internet about this.

Just search for "Ford Escape 2013 coolant by-pass solenoid". The coolant by-solenoid is generally located on top of the engine. After you make that search you'll get a good point of view. The repair involves removing coolant from the engine....

Q: Check engine light on inhibitor switch

Hi there. Thanks for sending in your question. It's less likely that the inhibit switch is the source of your vibrations or symptoms. It's more likely that something else, such as worn out engine mounts, a vacuum leak or a...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...