SES Won't Reset
 

Sorry if this has been addressed before, I've searched but haven't seen anyone with the same exact issue.

My 2000 Z28 just hit 50,000 miles, and almost immediately after it hit 50K, the service engine soon light came on. I ran the code at autozone and got P0442, so I thought it was probably a loose gas cap. I refilled, tightened up and drove about 50 miles over 3 days but it didn't shut off.

Next I removed the PCM/BAT fuse for about 10 minutes, still the light stays lit. I even disabled my theft lock and disconnected the battery negative terminal for 15 minutes but the light remains.

So my questions are:

1) Am I doing something wrong when trying to reset the light?
2) do I need to buy a code scanner to reset it?
3) If it was something else triggering the trouble code, shouldn't it at least go off temporarily before coming on again? Or is the fact that it won't reset a sign of something more serious?

I'm trying to avoid bringing it in to a shop, DC labor rates are through the roof.

Update: I disconnected the battery again but this time I left for 30 minutes and flicked the lights on for a few seconds to drain anything in there. Lights off, took a mile loop and it's still off. So far so good.

Sounds like you may have solved the issue. You can grab a handheld obd2 scanner for $30ish or so if it happens again.

P0442 is Evaporative Emission Control System Leak Detected (small leak).

The fuel tank cap is just one of several things that can set this code. Rubber hosing, tubing, connectors, any of these can have a leak.

The PCM doesn't check the evap system continuously. If the leak still exists, the PCM will set the code the next time it does it's test routine and illuminate the SES light.