1999 Toyota Corolla p0441 & p0446 codes. How to begin trouble-shooting
I have a 1999 Corolla, 226,000, 1.8L automatic. Check engine light came on recently indicating p0441 & through a second OBD reading (I was curious) at a different store indicated p0441 AND p0446. I bought a new gas cap as I suspect it was overdue (could smell gas). Suggested replacement for the p0441 code from one auto discount chain said likely solution is “replace Vacuum Switching Valve (VSV). I recently replaced my front end brakes (drums, rotors, calipers) and purchased 2 new tires - seemed reasonable (yet big ticket item) and fit my cars replacement timeline for these repairs. I intend to change out PCV valve as it’s probably overdue too.
My question is how can I, if possible, begin to trouble-shoot this issue on my own? The car is going into the mechanics (reliable) in about a week. My concern is that this possible fix (via the mechanic) could be pricey (charcoal canister, etc.). Also, I don’t fill up the tank (about 3/4) due to leak when filled to tippy top. My mechanic is aware of this and has said 3/4 tank (max) is fine. I suspect that this may be the definite beginning of the end for this car. If those codes had popped up prior to my brakes having been replaced, I think I would have nixed the whole thing and junked the car. Any feedback would be much appreciated. Thanks.