2008 Dodge caravan 3.3 engine I have 3 evap codes p0401,p0455,p0456

I have 3 evap codes p0401,p0455,p0456 I mean a couple videos saying these chryslers are known for the esim I know when I open the gas cap I can hear pressure release so didn't think I actually have a leak is there a way of testing these esim ? I don't just wanna change it I wanna test it any help would be appreciated. Thanks

Testing instructions for each code can be found here

www.eautorepair.net or www.alldatadiy.com

Purchase a subscription for a length of time and you will have the test info under the dtc (trouble code) list.

You have two different problems. The p0401 is an egr system problem, the 455 and 456 are evap problems.

Smoke testing would be the best diagnostic tool. If not, you could remove the esim and bench test. Apply pressure at the vent tube plug off the open end and check for air leaking. Most likely at the open end that connects esim to canister. Use soap or water to look for leaks.

A bidirectional scanner to run the EVAP Service Bay Test and a smoke machine is usually needed to make a conclusive call on these systems, IMO. Failing ESIM switches will flag EVAP leak codes just as readily as actual leaks will. :silly: I know you heard a pressure change while pulling the cap off, but that doesn't mean it's not leaking anyway.

If it helps at all, the presence of the P0456 SUGGESTS that the ESIM switch closed at some point, which means the wiring for the ESIM switch is likely OK and that the switch isn't unplugged. Because the ESIM is a switch input, the PCM is not able to check for opens or high resistance in the switch circuit. Only a dead short to ground on the signal wire.

Testing the ESIM switch itself for functionality isn't easy. It uses a weighted check valve that has to sit vertically to work correctly. The valve seals at a specific amount of vacuum, but vents excessive vacuum and pressure. In other words, it's usually easier to prove out the rest of the system.