Honda Civic 2008 Coupe Speedometer

I took my son’s 2008 Honda Civic Coupe in for an oil change at a local third party shop today. While there, I was persuaded to let the mechanics carry out a fuel injection service. On driving home I noticed that the digital speedometer no longer read correctly. It now reads about 20 mph over. This is particularly noticeable as the vehicle slows down. I saw that the mechanics were having trouble connecting into the fuel system. They were working in an area behind the air filter, and just in front of the instrument cluster. I believe that they may have disturbed a cable or something in that area, which has caused the problem. I plan to take the vehicle back try to get the shop to fix it, but can anyone please provide me some technical input. I have a basic knowledge of modern cars, but am not an expert. Thank you in advance.

This looks to have been a false alarm. On the way back to the shop to complain I noticed that the speedometer was reading ‘kph’. I soon located a button on the dash board that switches between ‘kph’ and ‘mph’. I guess that one of the mechanics must have pushed the button by mistake. It does seem a little weird though, as one has to hold the button for a few seconds for it to switch over. My apologies for wasting anyone’s time.

On a different note; your car does not need any fuel injection service…