Troubleshooting EVAP System Leaks A Practical Guide for Professionals

... host after EVAP valve. Success. No leak. So the system is leak free from after EVAP valve to canister 3) Now checked the EVAP valve it self. It may take some time before the light goes off. I think it took mine 3 or 4 days(different make). Clean the filler neck contact area and gasket ... The most common causes for EVAP leaks include bad seals and O-rings, a failing purge valve, a damaged hose or vent, or a defective leak ... I've looked over the hoses and they all appear to be connected. The ones related to the purge valve under the cover are in decent condition. If you see a P0442 DTC, you know there is a fuel vapor leak somewhere in the EVAP system. The small leak code tells you that the leak is probably minor. First: Check your vacuum lines. It is most likely due to a split or dry rotted line. Next step: Check your fuel tank hoses and the purge valve ... One can be something shorted electrically and caused the evap code or there is an oil or transmission leak that will need to be checked as well. The way the system determines that there is a large leak is by pressurizing the system and seeing if it holds using the leak detection pump. An EVAP system leak will always trigger the check engine light on your dashboard, and as you can imagine, this can cause quite a bit of worry. An EVAP leak occurs when there's a break or fault in this system, allowing fuel vapors to escape. This could be caused by something as simple as ...