Or
the car's brain [PCM] has the wrong tyre size parameter (could the garage have changed it when correcting some other fault?) which is used to calculate the speed.
If the MOT place has damaged it then it is their responsibility to repair it. You need to contact them asap.
Take it to a authorized dealer and tell them that you have problems with the Odometer they can usually correct it for you.
Tell me how you know this.
my ford fiesta mk 6 has just come back from the garage after having an MOT and now the speedo is reading 10 mph less than its actually travelling. can anyone tell me what may have caused this and can it be easily fixed, Thanks
