When you pump fuel into your vehicle’s fuel tank, the vapors from the fuel will build up in your fuel system. Fortunately, car manufacturers have installed an evaporative emission control system in their vehicles to prevent those fuel vapors from escaping the fuel system and going into the outside air.
Why are fuel vapors bad? Well, they contain dangerous hydrocarbons which pollute the environment. When hydrocarbons are exposed to sunlight and air, they generate smog. If you’ve ever driven in Los Angeles, then you know what excessive amounts of smog look like. Not only does it reduce the quality of the air that people breathe, but it contributes to the global warming crisis facing this planet.
Therefore, it is important for every vehicle to have a functional evaporative emission control system to prevent these vapors from getting released. However, there are times when certain vital components of the system may go bad or stop working. One common problem in the system has to do with the vent valve solenoid. If that malfunctions, then additional hydrocarbons will get released from the fuel system and hurt the environment.
The symptoms of a bad EVAP system vent valve solenoid include a Check Engine warning light turning on and a fuel odor in the cabin. You won’t experience any driving issues, but the Check Engine warning light should prompt you to find out what the problem is. If you run a diagnostic scan on your vehicle and you receive Trouble Code P0449 in response, then it confirms you have a malfunction in your EVAP system vent valve solenoid circuit.
- P0303: Cylinder #3 Misfire Detected
- P0102: Mass Air Flow MAF Circuit Low
- P0302: Cylinder #2 Misfire Detected
In this case, you can start investigating the possible causes of this problem. If the evaporative vent valve is in good condition, then you might have a bad carbon canister or fuel tank. There may be an issue with the electrical connection or with the EVAP system hoses. Sometimes the cause may be as simple as the gas cap being loose. That would certainly be the easiest and cheapest component to replace.
A professional auto mechanic can guide you on this problem. Let them investigate the internal components if your gas cap is not the issue.