Dredlocks9

Good morning, yesterday after driving my 2005 WRX I was greeted with the following Error: P0502 and my speedometer subsequently stopped working. My handbrake indicator and ABS lights would not go off the dashboard either. My temperature gauge was behaving abnormally I live in the tropics and has since gone back to normal operation.
Some history: I would have had a similar Speedometer issue 2 years ago and it turned out to be the small plastic speedo driven gear in the transmission. I had also changed the electronic vehicle speed sensor at this point.My clutch was changed and I went with a lightened flywheel.
Clutch judder issues were resolved last November by a professional tuner.
I had a new radiator, thermostat, water pump and timing belt installed earlier this year so I am unsure why my car was overheating briefly yesterday. My car is stock for the most part with the only real change being straight 2.5 exhaust from downpipe connection and Greddy profecII EBC.
Can anyone offer some suggestions on where to start troubleshooting the mentioned issue? The handbrake indicator has gone away but the ABS light is on steady despite ECU reset (disconnection of negative terminal and via OBDII adapter)

Your assistance is appreciated.

Regards