Hello to you. 

 

Should I be concerned that recently my engine has been reaching temperature very quickly? It does not overheat. I have no error codes and my long term fuel trim is +3%. 

 

I know it's summer but I'm sure last summer it didn't warm up this fast. I'm talking like 90 degrees in three minutes. I don't want to damage my engine. 

You could have a partially stuck thermostat or could be a faulty CTS. If you have vcds you can get live data stream for coolant temp, also some Bluetooth obd2 readers can do this but not as accurately.

I had also been thinking that mine has been warming up quicker than usual but just put it down to the recent warm weather. Probably nothing to worry about if your temp gauge gets to 90, stays there and the fans kick in when they should.

 

If you have diagnostic tools (VCDS, Torque Pro or similar) then you could try logging the actual coolant temperature.

If I had a vac leak would that cause a fast warm up? Would a vac leak show up on the fuel trims or not? 

It is worth noting its exceptionally hot weather at the minute.

During winter your cold start was happening with an engine bay at (potentially) sub zero temps. 

If your car is catching a lot of direct sunlight, it could be a cold start at nearer 30-40degrees... 

Id not be worried too much, until temps cool back down a lot and see what it does then. If its the same, likely cause is a failing CTS or Stat as said above

My diesel is also warming up faster than normal ATM. Once the actual coolant temperature goes above ~60C the reported value on the gauge tends to go to 90C or thereabouts and stay there.

I'll keep an eye on it see how it goes