What is a gas cap replacement?
Replacing a gas cap involves very little labor but may require extensive inspection. If your gas cap isn’t obviously broken or missing, your mechanic will have to rule out problems with the fuel pump, fuel lines, fuel tank, and fuel filter as well.
If you’re due for a California smog test, make sure to fasten your gas cap tightly beforehand.
How do I know if my gas cap needs replacing?
You might need to replace your gas cap if you notice the following warning signs:
Your vehicle fails a smog or emissions test
Your check engine light is on
Your garage smells like gasoline
The computer system in your car might also be able to detect the consequences of a loose gas cap, like decreased fuel pressure. However, you won’t know why the check engine light is illuminated unless you have an OBD code reader.
How long do gas caps usually last?
Gas caps can usually maintain an airtight seal for at least 50,000 miles. They aren't high-impact, high-wear car parts, so your vehicle's manufacturer might not even list an estimated lifespan. Considering how cheap they are, replacing an old vehicle's filler cap could be a good idea.
Can I do a gas cap replacement myself?
With zero equipment required (just the knowledge of how to screw a lid on a jar), you can perform a gas cap replacement yourself. If you’re feeling fancy, you can add a tether or upgrade to a locking fuel cap for as little as $1 extra.
So why would anyone visit a mechanic to replace a gas cap? In most cases, the problem is not with the installation, but with the diagnosis. You may not notice subtle signs of malfunction like emission control problems or reduced fuel economy, if your gas cap isn't obviously damaged or missing.