EVAP Leaks and How to Find Them
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What is an Evaporative Emission System (EVAP) leak?
An Evaporative Emission System (EVAP) leak is where fuel vapors that are contained in the EVAP system escape. When fuel vapor escapes, it can be harmful to the atmosphere. Any EVAP system problem should be resolved quickly to prevent further damage to the environment.
What are the symptoms of an EVAP system leak?
A common symptom of an EVAP system leak is a fault code, but in some cases, there can be a fuel smell around the vehicle.
How serious is an EVAP system leak and should you be worried?
Most EVAP system leaks are not serious, but should always be checked by a trained professional.
Here are some common EVAP leak fault codes:
P0455 – EVAP system gross leak detected
P0456 – EVAP system very small leak detected
P0442 – EVAP system small leak detected
P0440 – EVAP system malfunction
P0441 – EVAP system incorrect purge flow or flow during non-purge
P0457 – EVAP system leak detected (fuel cap) or EVAP canister
Potential causes of an EVAP leak can include:
Gas cap failure
The o-ring on the gas cap can become worn over time.
The gas tank filler tube is damaged
If the gas tank filler tube is rubber, it can become cracked and cause a leak.
Purge valve or Vent valve malfunction causing a leak
The mechanical devices can become stuck and not allow the EVAP system to become sealed.
Fuel vapor lines are damaged
Road conditions can damage fuel vapor lines that run underneath the vehicle.
The charcoal canister is leaking at a seam.
The charcoal canister is made of plastic that has seams. Leaks can occur at these seams.
Can you pass an inspection with an EVAP leak?
The short answer is no. A check engine light with an EVAP system fault code will not pass an inspection.
How would a mechanic find a leak?
A mechanic uses a smoke machine that is directly connected to the EVAP system. The mechanic seals the EVAP system with a scan tool’s control or by physically blocking off EVAP hoses. As smoke fills the EVAP system, any smoke that leaks out will be noticed.
How long does it take to fix an EVAP leak?
An EVAP leak can take hours to present itself. With the right tools, the amount of time spent can be drastically decreased.
Depending on the size of the leak, it can still take a large amount of time to find.
How much does an EVAP leak repair cost?
An EVAP leak repair costs the number of hours spent to find the leak plus the cost of parts and labor to complete the repair.
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