Mike S.

I have a 1996 F-150 with the 4.9 I-6, 170 k miles and still going strong. I have no detectable driveability issues, but got the dreaded check engine light and the auto parts store pulled code P0443. A little research led me to check the purge valve on the firewall. I followed the hoses in and out and did not see any leaks. There is 12V at the connector with the key on, and the valve resistance across the terminals is 31 ohms.

I'm not a mechanic, but financial necessity and some electrical knowledge got me this far. Is there anything else to check that doesn't require special tools or ability?

I'm thinking maybe the main computer (PCM) is bad. Any idea how much these things cost? Are they a Ford-only part or aftermarket? Is my best bet to go to a pro at this point?

Any advice is appreciated.

BigGreyBox

Doubtful its the computer, it probably wouldn't let you check codes in that case. The code is for your evap canister. Its either leaking or the solenoid is bad. With the truck running you can check for vacuum leaks, and if you have a haynes or chiltons manual I'm sure there's a way to test the solenoid.

Mike S.

I do have a repair manual -- not sure which brand -- red cover.

Forgive me if this is a stupid question, but how do I check it for vacuum leaks? Do I need a special vacuum gage?

I'll check the repair manual for a solenoid check procedure.

Thanks!

BigGreyBox

Just start the truck up and feel along the hoses and the canister, if its a decent sized leak you'll feel it. If your vacuum lines are cracked and brittle you might as well just replace the bad stuff, its super cheap. But if you have a vacuum leak you might even be able to hear or it feel it in the idle.