The temperature gauge in my 2006 Toyota Avensis 2.2 keeps reading high. I got the car about a month ago and it has only happened twice. I took the car to a garage the day after it showed high the first time but when I got there it was back to normal. The garage confirmed all the engine temperatures were okay and reading as normal, though couldn't explain why the gauge was reading high the day before. The last time it happened it was 1 mark off of the high mark and when I switched the engine off the temperature gauge stayed at same high position and didn't return to bottom position. It has been working okay for the last week but any advice would be appreciated.