OC Transpo says a glitch impacting some presto card readers is costing them hundreds of dollars a day in unpaid fares. 

"It's our database on the buses interpreting the GPS Data and sending that information to the presto card reader," said Pat Scrimgeour, the director of transit customer systems and planning at OC Transpo. 

Scrimgeour said the glitch started in late December after several OC Transpo service changes and fare increases. Since then, approximately $20,000 dollars has been lost and up to 12,000 trips have been affected. 

"It's a substantial amount of money, of course, but on the scale of the $200,000 million we bring in in fares every year, and that varies, it is a pretty low fraction," he said. 

The glitch is affecting13 separate and unspecified locations across the city. Scrimgeour would not elaborate on the 13 locations, but said some are former express routes.

He said the problem is not with the presto system itself but with an onboard computer system that tracks a bus' movement and relays that information to the card reader.  Right now, he said some of the readers have not adjusted to the new routes and think the buses have gone off course or are not in service and do not accept payment. 

The fix is in the works and should be complete within the next few days. The database update must be tested before it can be fully rolled out. 

Only pay-per-use riders are impacted.