My check engine light came on and the shop that I took it to said I had a code of P0442. They said I had to replace my canister, purge valve, and my gas cap. I was told I had to replace all three and if I didn't then it could affect my spark plugs. The hoses to my canister where dry rotted as well.
I just replaced my gas cap and the engine light went off. They said that can't happen and it will come back on in a few weeks and I still needed to make the repairs. They quoted me over $800. Should I wait to see if the light comes back on? And how do I know if I really need to replace the canister?
In some cases, the simple seal around the gas cap itself can fail. This too, sets the same code as if the canister was failing. It is possible that you may be able to just replace the cap, I recommend doing this first and seeing if it solves your check engine light for the long term. If the your check engine light returns, then you may have deeper issues. To save yourself money in the short term, I would wait to see if your light stays off.
I would wait and see if the code comes back. With a new cap, if it does come back, then you know that you'll need further work on the evaporative system. You may just get lucky and the new cap will fix the problem.
〉 Answered on Aug 17th, 2012 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines