An MP has written to Hertfordshire County Council asking them to refund fines to about 10,000 drivers prosecuted for using a new bus lane.
Transport minister and Hemel Hempstead MP Mike Penning said signs on Moor End Road bus lane should be made bigger.
Since the beginning of August, 10,000 drivers have been caught on camera in the lane and each faces a £60 fine.
A county council spokesperson said the signs conformed to guidelines set out by the minister's own department.
Mr Penning said he had been "inundated" with letters and wants the council to repaint the road red and to make the signs clearer.
"Ignorance in the eyes of the law has never been a defence but some of the signage is clearly wrong," he said.
"The thing to do surely is suspend any enforcement against people while they sort this out."
He has written to Caroline Tapster, county council chief executive, asking her to suspend enforcement action and refund any fines already doled out.