I have a digital dash in my 1989 cougar. the Odometer suddenly jumped from 83000 miles to 133000 miles and the speedomoter is showing double. What causes this. can i fix it?

Your odometor should continue to track miles and as led displayed Odometers and dash lights receive voltage on same line from headlight switch take it in for the dash lights and 400,000 mile club look out.

It's electronic. Probably a computer failure

Ho, that doesn't bode well for your tank monitoring. It was a fluke, but may keep doing it, if the odometer is a mechanical meter with numbers turning from the speedometer cable by plastic gearing that wears. Watch for it to jump at the next 100 mile turn over.
I understand your reluctance to change out the fuel level sender in the tank if that is why the gauge doesn't work. It is a lot of work. But have you checked to see if it's the dash gauge or the sender unit? A couple of electrical tests could determine that. If it is the dash gauge, that is comparatively easy to replace, and you could buy a used one-they seldom go bad. Otherwise, keep tracking your miles.

FFS find fuel soon.

You should be happy about this, the gear on the mileage may have broken or there are to many miles on it where it doesn't work anymore.

I believe the odometer may roll over at 100K. However, if there is a blank space for the first digit on the odometer, the driver for it may have died.

Most newer trucks and suv's have a digital odometer. the miles odometer and trip odometer are combinded. By pressing the little button that patrudes from the instument cluster will show you the orignal 226,335 miles. When you press and hold the button while the T__86.6 is displayed will reset the trip odometer. Some people use the trip odometer to monitor times between oil changes and tire rotations.

We had an experience with the Lincoln Digital dash and you may want to check your alternator first.

When our alternator shorted out we did not lose power: however the speedo and odometer showed 60 mph at idle with miles being counted on the odometer. Sometimes the mph changed when we started moving.

I replaced the digital dash and was lucky to find a used one. Because of the alternator the replacement dash did the same thing. Lots of work and money for nothing.

Took the alternator into Autozone (You can drive) and got free test. Replaced alternator and everything worked again. You should check your ground wires for the turn signals or change signal stalk.

The gear on the odometer is stripped. Quite the common problem with Audi's of this vintage. Parts available at: http://speedometergears.com/

To fix, you have to pull the gauge cluster, remove the speedo from the cluster, then remove the odometer from the speedo. The gear replacement is pretty easy once you get it all apart.