Started the car yesterday and for the first time, I heard a clicking sound in the engine I.e. Click,click,click..I have a 2009 xf sc auto.

What could it be?

 

Very loud? Does it change with RPM (faster at higher rpm)? Does it do it on cold start up and continue to do it until warm? Did you check to make sure the oil is still full? Any noticeable metal flakes on the dipstick? Post a clip of the sound.

Could be injector clicking as injectors can be fairly noisy which isn't necessarily a bad thing other than the noise. You could check all the plugs to make sure one didn't back out a bit. It could be as bad as a spun rod bearing meaning the engine is about to let go. Hard to say from your description. If it's under warranty bring it in.

 

I've always heard it occasionally in mine.

 

Thanks for the input. Drove car today and NO clicking..quiet and smooth. Occasionally is probably the answer and it should be no big deal...but I will look atnthe items recommended such as oil, spark plugs, etc. To be sure.

 

I wasn't trying to scare you I just know that tapping can mean a spun bearing. I build cars on the side and most of the business comes from people that blow up there stock motor and want something better. The motor starts tapping when a bearing spins (oil issue) and eventually shoots a rod through the block. That sound doesn't go away so you shouldn't have to worry about that.

Checking the plugs and the oil can only help you learn more about the car anyway.

I found these articles online that might be helpful:
http://www.2carpros.com/articles/clicking-sound
http://www.2carpros.com/articles/engine-noises