DTC PO 442..Defective/loose fuel cap..EVAP canister or hose cracked..Purge/Vent solenoid defective..Vacuum leak at engine. 99K orig. mi. I think emission controls are oem.

Don't know much about emission system, but will try alittle DIY before going to shop. So....

Replaced fuel cap. Started eng. & ses light still on. Q..Assuming it was a bad fuel cap would new one cause ses light to go off or do I have to clear code?

On top of eng. by v. cover is the "canister purge valve solenoid" with elect. wires. Has 2 lines (small plastic hose?)..one goes to intake. Other goes to I assume canister & some kinda part in it says "EVAP Svc. port 1 psi max. regulated pressure only". My Q. on "psi"....

Just guessing, but if this p. valve was working correctly, does that mean I would hear pressure escaping when I remove fuel cap? If so, didn't notice any with old or new cap. Also if eng. has vac. leak, not sure I will be able to find it. Long post, but appreciate any advice. Tks.

You would have to clear the code and wait to see if it will come back. This can take from a day of driving to several days of driving depending on how you drive.

that port is a test port, that just means dont put a bunch of pressure on the system. another problem area is those vacuum lines, on a car of your age(what i did to my 9 just replace all the ones from the canister to the purge valve(on the engine) and from the valve to the tb. and the boot specifically on the tb, that one gets cracked like a old tire and causes all kinds of trouble because the other line goes to the fuel pressure regulator.

and the evap code when you clear it takes quite a while before it tests it especially when its cold could be weeks

Did you replace the gas cap with an OEM one or aftermarket? Some of the aftermarket ones don't seal properly and throw a code. Best thing to do is whenever you make a change to eliminate the code, take the car to Autozone and have the code cleared. If you code comes back you will know for sure the problem has not been fixed. As is it now, the gas cap could have fixed the problem, but you won't know for a while until the code clears itself.

Tks. appreciate replies. Wifes car & cause its still running ok (so far) she'* gone. Meaning, on/off working on it. AZ did scan & got cap there. Its aftmkt not oem, but gasket looked ok compared to my old which was getting tiny cracks.

I can clear codes on my truck by disconnecting batts. I tried same on buick & after I started eng. SES light still stayed on? Maybe dosen't work that way & requires scan tool to erase code as mentioned. I'll ask AZ to clear it. If I still get SES light, then i'll gamble some more...

I'll replace the elect. purge solinoid, $35 @ AZ. Maybe its ok, just thinking its still old oem part. As mentioned, still vac. lines etc. involved. Couldn't detect any vac. leaks on top end & cking line going down/under to cannister will be pia. E.decal says its underneath at RR. Don't know yet?

FWIW...bought this car in "1999" with 6K mi. on odo. We talked over pros/cons on keeping it earlier this yr. New one not in budget, so decided to fix a few things & did. May have to rethink that after I get current problem fixed. Still looks good, drives ok, but ??? Tks. again.

Take a look at the top edge of the gas filler neck, where it interfaces to the gas cap, for any corrosion or irregularity in the surface that might prevent a good seal.

Update..Called AZ & was told because its an emission code they couldn't delete it. Some liability issue & store policy. They do have low end code reader & apparently it will clear codes. Right now looking like I need it. Just now getting big winter storm, so not going today. tks.

2KG..Oops..Didn't see your reply. Im new here & don't know yet if u can edit/add to previous post? I did check filler neck, surface etc. & all smooth/good. Tks.

Another update....

Had to make short/quick trip to store. On way back ses light went off. Maybe it was gas cap? Anyhow, not gonna do any more repairs right now. hmmmmm?

the way the conditions are it can be a week or a couple hours if the temps are right and you make a bunch of semi short trips. on any 96+ you have to clear the codes with a scanner all you do by disconnecting the battery is reset all the learned values like fuel and shift points, so you wont to avoid that if possible. you really need to have a scanner to do anything on these cars so at least a cheap one would be better than nothing. one with live data function is the better option because it will tell you how its running by giving feadback from sensors if the mileage is decreasing or its running bad but there is no codes which happens. i use a android app that is $5 called torque that does all that plus a bunch of performance stuff. you just need a bluetooth adapter that is cheap online. i probably have less into it than the "cheap" reader from az