My 2000 New Beetle blue engine temp light comes on normally when cold but also comes on intermittently when warm or having been driven for 30 mins or more.
It has the 2.0L engine, no mods...
Please help!!!

It sounds like you ECT is problably faulty.
Are there any codes stored or check eng. lights?

I don't have a computer module to check it with but the check engine light is not on.

2002 VW Beetle's fuel filler cap latch will not open by raising the filler cap switch in the driver's door.
Is this an electrical problem?
If so, which is the fuse I have to look at?

Codes can still be stored in the ecm even if the check engine light is not on. THe temp sensor is on the driver side of the engine under the cover. It sticks out of a plastic coolant pipe straight up right off the cylinder head. look to see if the sensor is green. If the sensor is black then you need to replace the sensor and o-ring (about 8$ in parts). That should fix your problem. Also dont forget to top off the coolant with new vw coolant if you replace the sensor.