It depends

I have a CEL (not blinking) on my dash. I recently filled the tank.
I opened and reclosed the gas cap.

If that 'solves' the problem, how many start/stop engine cycles will it take to clear the error light? Or must it be reset via ODB2/mechanic?

Can someone suggest from Amazon a cheap ODB2 reader that will let me look up any error codes? I seem to remember the 2000 Boxsters weren't readable by all hardware back in 2000 or weren't standard or something. I once had my car 'fail' NJ inspection because the nearby mechanic I paid to do the inspection had out of date software that wouldn't recognize the car - had to jump through hoops to 'fix' the failure when there was nothing wrong.

So - how long to clear (if it clears)? and cheap ODB2 reader for 2000 Boxster.

Thanks all

Andrew

(If this is a double post, my apologies. The first version disappeared from my screen).

Any code reader - even a $20 HF, walmart or autozone will clear most codes. Most will give you the obvious fault readings too. You will not likely get freeze frame or real time data though. But it sounds like you do not need that.
My local AZone will read and clear codes for free. But there is often a wait for a tech.

If you have the radio codes, you can also disconnect the battery for 10 minutes and it should reset as well and for free.

Note - you MUST have the radio codes or you will have a trip to the dealer.

If the code comes back, and it is not something obvious, then you might need a more expensive reader.

So I bought a cheap ODB2 reader from Amazon:
OUK-BT OBD Scan Tool, Red Universal OBD II Car Diagnostic Scanner Code Reader Automotive Fault Diagnostic Tool for All OBD2 Protocol Compliant Vehicles

for $16 + tax

The device had no problem recognizing the car and reading the error - great $16!.

It read and I cleared a P0440 - which may indeed be due to the gas cap.

Now to see if the error, on my 22 year old baby, returns - which would mean yet another trip to the car doctor (Prevost Motorsport in Bordentown, NJ).

Thanks for the help, guys.

Andrew

How long it takes for a check engine code to clear depends on the code but typically it takes a couple of drive cycles (varied driving that includes going from fully cold to fully hot). I suggest you continue to drive the car normally and if the code doesn't clear automatically after some time then take it to an auto parts store and ask them to read it. As long as the light isn't flashing and the car is running ok, it's almost certainly not a big deal.