RPM meter always remains on Highest side on 2002 Honda Civic

I saw 2002 Honda Civic LX model its private deal, and the car was hit from Side on highway, and my mechanic says the car looks fine, but only problem is that the RPM meter which is besides Odometer which shows RPM always remains at high point that is above 8 and 9 even if engine is off, I dont understand why, my mechanic says it could be due to Odometer tampering, so if any one has any clue about this situation please let me know. This would be my first car, and I am really naive person in terms of Car, so all kind of replies and answers are welcome.
Hope a positive and prompt reply from my friends.

Asked by for the 2002 Honda Civic
Hey Raja,
This is a difficult problem to solve without actually performing a diagnosis on the RPM Gauge and wiring. I don't know about the odometer tampering, put if someone was in there messing around, it's possible they affected the RPM gauge. How many miles does the vehicle have on it?
I appreciate your reply, the mileage on car is 158,000 kms, and the guy showed it to Honda dealer and they are saying it to fix for 200 dollar, so do you doubt it as engine problem, as he owner of the car has already forwarded me all service details regarding the car, and in 2008 the timing belt was changed by Honda. I would appreciate your reply again.