Check Engine Light on again p0455

Within the past month I have had the light come on three times. I have taken it to South Atlanta Toyota to get it fixed and have spent almost $2500. Now it is on again. Looks like I'll need to take it somewhere else. It's about $1200 every time I walk into that place.

 

Get the EVAP system smoke tested. Most shops can do it - not just dealership. Probably a bad vent control valve. Even new replacement parts can be bad off the line.

 

Hi. Thanks for that tip. I called them and they said they did the smoke test. We agreed that next week I'll take it in and we will have a meetup with the service advisor, the mechanic and the service supervisor. Maybe it's a bad sensor that's giving the reading but it appears to take a few days after I take it home before the CEL comes on again. I have the Ultragauge so I can immediately see the codes it's throwing. Same old p0455 - major leak in evap system. They have replaced parts that they said had been chewed on by rodents, replaced the fuel tank, charcoal canister and a valve but still get the light. I tightened the gas cap, cleared the codes and turned of the light but it came back on.

 

Replaced the fuel tank in an 06?

 

It sounds like they may have just replaced parts instead of actually testing anything.
I would want to first of all verify wiring integrity and make sure the leak detection pump, valves, and pressure sensor all work properly.
Toyota's code troubleshooting guides are pretty useless for the most part IMO, it comes down to finding someone that understands how the system works to properly diagnose it.
I've learned with EVAP systems just because the code is for a leak doesn't always mean there's actually a leak, many other things can trigger leak codes (a skewed sensor, wiring, a stuck/plugged valve, etc).
If rodents actually caused it initially they could have came back and chewed the same stuff as they tend to do if you don't park in a different area or eliminate them.