Q: Gas cap loose and check engine soon light comes on

asked by on

My gas cap says loose I replaced gas cap and it still says it and check engine light comes on what could be the problem

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

Hi there. The vehicle’s computer can think that the gas cap is loose simply from there being a leak in the EVAP system. This will occur if the gas cap neck is not sealing well to the cap, or if there is a leak someplace else in the system and the check engine light will keep coming on and off.

Smoke test the system to find the leak as it may be a solenoid or a small hose leak that can be hard to find. If you are planning on having this EVAP system problem checked, consider getting a certified mobile technician, such as one from YourMechanic, to come to your location and see why the check engine light keeps coming on. If you suspect that the problem is due to a loose gas cap, get the cap inspected as well.

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 cap loose and check engine soon light comes on

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: Bike switches off while driving

Depending on the type of fuel valve you have you should remove the fuel valve from the fuel tank to clean or replace the tank filter screen mounted on the fuel control valve. The filter is most likely clogged with...

Q: Engine is running rough and P0401, P0171 and P0174 codes.

The first thing to check is to see if the EGR solenoid will release the vacuum when the electrical connector is disconnected. If it still doesn't release the vacuum then the solenoid should be replaced. The codes need to be...

Q: Battery plate

Hi there: It depends on where the hold-down strap is located that is rusted. If there are two individual bolts on either side of the battery, you can cut the one closest to you that is easier to access and...

Related articles

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...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...