But after the break the visitors gave a better account of themselves and Everton loanee Garbutt added to his goal against Sheffield United in the FA Cup with a low drive after 76 minutes to earn his side a point.
Preston went into the game with a six-game unbeaten run in all competitions and controlled the early stages, Garner and Kevin Davies both going close with headers.
But just when it looked like Colchester would hold out until the break Garner netted to give the home side a deserved lead.
However, the visitors were much improved after half-time with Marcus Bean heading just over on the hour mark.
And the U's earned themselves a draw at Deepdale when Garbutt's low drive found the bottom corner of the net.