Your vehicle depends on the evaporation emission control system (EVAP system) to make sure that hazardous fuel vapors do not escape the gas tank. The system contains a charcoal canister with charcoal pellets which absorb the fuel vapors. The engine control unit monitors the vent control valve so that air enters the charcoal canister and moves the fuel vapors toward the engine air intake manifold. The purge valve helps guide the fuel vapor flow to ensure it reaches the engine just fine.
Once the fuel vapors enter the engine, they’re ignited in the combustion chamber along with the fuel and air. If you have fuel vapors getting burned in the engine, they’re not getting released into the atmosphere and causing problems for the environment. But if there is a leak in the EVAP system, then it’ll work against this effort to protect the environment and keep the air clean.
If you ever notice a fuel odor in the cabin and the Check Engine warning light illuminating on the dashboard, then you could potentially have an EVAP system leak. A poor fuel economy might also be present as well. When you notice these problems, run a diagnostic check on the powertrain to discover the problem. If you receive diagnostic code P0442, then it means you have a medium-sized leak coming from your EVAP system.
You might feel tempted to ignore this problem because your driving ability will not be impaired. However, you would fail an emissions test if you are required to get one in your state every year. But even if an emissions test was not the issue, think about protecting the environment and keeping the air clean for everyone to breathe. You can do your part by fixing or replacing the necessary components which are responsible for this medium-sized vapor leak in your EVAP system.
- P0455: EVAP System Large Leak Detected
- P0300: Random/Multiple Cylinder Misfire Detected
- P0171: System Too Lean Bank 1
EVAP systems can have different size leaks, resulting in different diagnostic codes. The possible causes of medium-sized leaks are like the causes of other leaks. Check to see if you have a loose fuel cap, damaged fuel cap, or leaky fuel tank. If you don’t see these problems present, then you can have an auto technician check to see if you have a bad purge valve, bad canister vent valve, leaky charcoal canister, or leaky EVAP hose.