If you're the high bidder on an auction with a sale status that's either on Minimum Bid or on Approval you must wait for the seller to accept, counter, or reject your high bid. 

For the auctions marked with the sale status on Minimum bid the seller has until 6:00 pm PST one business day after the end of the auction to: accept your bid, counter with a higher bid, or reject your bid. 

For the auctions marked with the sale status On Approval the seller has until 6:00 pm PST two business days after the end of the auction to: accept your bid, counter with a higher bid, or reject your bid. You'll receive the seller's response by email. 

At any point during the approval process you may: increase your bid to the next highest increment, keep your current bid (do not increase the bid), or accept the seller's minimum bid. You can increase your bid or accept the seller's offer from the auction page. If the seller accepts your high bid within the approval window you will be obligated to purchase the vehicle.