Skip the auto shop - Our mechanics make house calls

Q: Hissing noises coming from the gas tank area

asked by on

Recently, the van started making unusual hissing noises. I tried to pinpoint where it is coming from and it seems to be originating from the gas tank area. The noise lasts only for several seconds in intervals, which can last up to a couple of minutes. The noise is similar to air being released, or as if the water is running in the next room. It occurs after the van sat for a while and also when the weather is very cold. What could be the problem?

Hey there. From your description, it sounds like you are hearing the Evaporative emissions system perform its routine checks. The computer will check the fuel tank and evaporative emissions hoses for leaks. If conditions are right, the pressure will build inside the tank during testing and the computer and may vent that pressure causing a hissing sound. Look to see if your Check Engine Light is on. That may indicate that there is a leak in the evaporative emissions system that is causing the hissing sound. If the light is not on, I wouldn’t worry much about the noise as I believe this is normal. If the noise seems to worsen in any way, or you begin to notice drivability concerns, have a local expert, like one from YourMechanic, diagnose the noise in order to determine what is going on.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: P0401

Hi Mushi. Thanks for writing in today. Sometimes the initial diagnosis based on the error code is not the actual source of the problem. In the case of the P0401, the code indicates that that the engine control module (ECM)...

Q: Backup sensor out

The rapid beeps are actually an indication of which sensor is out. If the beeps are rapid and non-stop it is probably the right side sensor that needs replacing. The right rear sensor also makes many beeps but will typically...

Q: Car starts fine sometimes but idles out after pressing the gas.

Hi and thanks for contacting YourMechanic. If you start your engine and it runs fine, then when pushing on the gas pedal then engine starts to rev up and then goes to an idle, this is an issue with the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
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...