Hundreds of motorists who followed a diversion during serious flooding have been sent fines.
Police directed traffic down a bus lane when an overflowing sewer closed Gdynia Way in recent deluges.
But new enforcement cameras were left switched on – and £60 fines are now landing on outraged drivers' doormats.
Council workers have now been told to write to everyone who was issued a penalty charge notice (PCN) during the Gdynia Way flooding fiasco.
Five days' worth of fines triggered by a camera in Embankment Road are to be torn up, the local authority says.
Businessman Michael Freeman received fines totalling up to £120 after his company's van was twice caught on camera along the stretch. The PCNs are 'discounted' to £30 if they are paid within two weeks.
Jobel kitchens boss Mr Freeman said: "I was going to Plympton when I got done and Gdynia was shut.
"The police were diverting the traffic across Embankment Road and, if the police are diverting you that way, that's the way you go.
"It's just crazy. If Gdynia was shut, they should have just turned the camera off.
"How much is it costing to send out fines and then letters canceling them?
"It's like one hand doesn't know what the other is doing."
Mr Freeman said he rang up to complain after receiving the first of the fines and was told he could appeal.
"But the worry I have is that some people will just pay it," he added.
As revealed last month, six bus lane enforcement cameras have generated nearly half a million pounds in fines for the council since being turned on in August.
Gdynia Way, the main route into Plymouth from the east, was closed several times by an overflowing sewer as floods hit the city just over a week ago.
Plymouth City Council said anyone snapped by the bus lane camera in Embankment Road between November 20 and 25 would have their fine cancelled.
A spokeswoman said: "Gdynia Way was open to all traffic at the time Mr Freeman drove through the bus gate on Embankment Road.
"However, the extreme weather conditions last week meant the road did need to be closed or partially closed a number of times and we appreciate this may have been confusing for motorists.
"We have therefore decided, in light of the exceptional circumstances, to cancel all penalty charge notices issued by the Embankment Road enforcement camera between Tuesday, November 20 and Sunday, November 25.
"All motorists issued with a PCN during this time will receive a letter confirming this."
A police spokesman confirmed officers had directed traffic along Embankment Road during the closure of Gdynia Way.