Hi Maggy,
The outside temperature reading could be because the wire to the exterior temp sensor is damaged or broken. I had rabbits eat through mine, and the outside temp reading was -xx F (don't remember exactly, but it was wrong). I fixed the wires, and the outside temp now works. One quick check of the CAN BUS is to measure the resistance on the CAN BUS (it's between pin 1 and 11 on one of the ECU connectors (i don't remember which ECU connector, but that's in the service manual)). It should read around 60 ohms. If you have an intermittent CAN BUS failure, then one symptom is all the dash lights coming on while the car is driving.
Good Luck
-Jerry