Several home defenders stood off Carter who had space to deliver a 30-yard piledriver which flew into Paul Henderson's top right-hand corner.
Ironically, the only other time Preston had threatened was after just 30 seconds when Henderson had to be alert to block Craig Beattie's close-range shot.
Sheffield Wednesday's survival hopes were dented after a home loss to promotion-chasing West Bromwich Albion, with a 90th-minute winner again deciding the result.
Kevin Phillips stepped off the bench to snatch a spectacular win, when the 34-year-old striker steamed in to meet substitute James Morrison's cross to head home.
Wednesday are unbeaten in three games but still in deep trouble in the drop zone.
Colchester remain rooted to the foot of the table after a 4-1 reverse at Plymouth Argyle, and are now seven points adrift of safety.
This game was drifting to a drab stalemate at the Walkers Stadium when Darren Carter stunned the Foxes with a last-minute thunderbolt.
Several home defenders stood off Carter who had space to deliver a 30-yard piledriver which flew into Paul Henderson's top right-hand corner.
Ironically, the only other time Preston had threatened was after just 30 seconds when Henderson had to be alert to block Craig Beattie's close-range shot.
Sheffield Wednesday's survival hopes were dented after a home loss to promotion-chasing West Bromwich Albion, with a 90th-minute winner again deciding the result.
Kevin Phillips stepped off the bench to snatch a spectacular win, when the 34-year-old striker steamed in to meet substitute James Morrison's cross to head home.
Wednesday areunbeaten in three games but still in deep trouble in the drop zone.
Jason Euell's late, late show earned ten-man Southampton a dramatic share of the spoils against Wolves at Molineux and boosted their survival hopes.
Saints, who have not been beaten by Wolves in 28 years, looked to be heading to a damaging defeat after two goals from Sylvan Ebanks-Blake either side of a Gregory Vignal equaliser from the spot.
Vignal was then dismissed for an 81st minute bust-up with Ebanks-Blake, but Southampton were rewarded for their never-say-die attitude in the fourth minute of stoppage time.
The unmarked Euell rose above the Wolves defence to head home a corner from Mario Licka to earn new Saints boss Nigel Pearson a third successive draw.
eaders from Alan Lee and James Beattie cancelled each other out at a chilly Portman Road as Sheffield United edged closer to safety, while Ipswich slipped out of the play-off places.
Beattie struck first from close range on 32 minutes to put the Blades in front, but Lee replied eight minutes after the interval and overall a draw was probably a fair result on the night.
n eventful game at the KC Stadium saw Hull City come out on top against Burnley after first-half goals from Fraizer Campbell and Richard Garcia.
The second half saw a total of four red cards, with Caleb Folan and Jay-Jay Okocha seeing red for Hull and second yellows being handed out to Steven Caldwell and Joey Gudjonsson for the Clarets.
Bristol City remain at the top of the table after a 1-1 draw with promotion-rivals Charlton Athletic at The Valley
Hull took the lead on 14 minutes as Campbell made space for himself inside the Burnley box and hit a right-footed effort from 10 yards which saw the ball sneak under the body of keeper Brian Jensen.
The Tigers were 2-0 up on 28 minutes as Garcia found himself in space 30 yards from goal and the Hull man fired in a right-footed shot which saw the ball rocket into the top right corner.
Watford moved back into the automatic promotion places, but paid the price for not building on their first-half superiority as Jamie Cureton's superb strike earned Norwich City a 1-1 draw.
There appeared to be only one winner at the interval after Dan Shittu had headed the Hornets in front, but Aidy Boothroyd's side seemingly got caught in two minds after the break, not sure whether to push on for a decisive second goal or protect what they already had.
In the end, they largely opted for the latter and the Canaries duly capitalised.
Blackpool's Gary Taylor-Fletcher and Barnsley's Jamal Campbell-Ryce cancelled each other out in a 1-1 stalemate, while Crystal Palace and Cardiff played out a goalless draw at Selhurst Park.