Unveiling the Secrets of Evap System Leak Detection

The only way the evap system can purge (into the engine) is through the purge valve. Otherwise it would just leak into the atmosphere. The EVAP canister purge valve, which is fitted in the line from the EVAP canister to the plenum, is controlled by the ECM which determines the ... I would normally say that an evaporative leak is not a problem as I deal with that all the time. Very few of them are loose or defective gas caps. The P0456 code indicates a small leak in the EVAP system, most commonly caused by a faulty gas cap. While not usually an urgent issue, it should be diagnosed ... The evap system is emissions venting for the gas tank. Nothing to do with radiator, AC, or engine vacuum lines. An EVAP system can have first check to see if the cap is tight and seals against the filler neck. Next remove the cap to inspect the cap O ring seal. The light comes on for a small evap leak, I fiddle with the gas cap and erase the code, and it stays off for anywhere from a couple days to a couple weeks. The majority of the time I've thought it's to do with EVAP system parts like the charcoal canister, purge valve, lines etc. but just the other ... Check filler neck, rubber hose from filler neck to tank, charcoal canister and associated hoses and such. A broken hose anywhere in the system ... Find your TRQ parts here: http://1aau.to/m/ETCG0455 Eric the Car Guy is here! He's visiting TRQ to explain check engine codes to you!