Hopefully i can help..
Has there been work done recently on the car?
Have you had to jump start or had any battery issues recently?
Battery went completely flat
Hi..there thanks for getting back..
Sometimes a totally flat battery or even jump starting can corrupt the odometer and it to read out the wrong mileage display..also for instance boosting a flat battery with a subsequent rise in voltage can sometimes affect the odometer too the same way..The only thing i can advise from here to be honest or try anyway is to seek a mileage correction/recalibration service locally..you more than likly find them in the yellow pages/or any specialist diagnostic technician locally provided they have the equipement and see wether they can correct it through their equipment and basically get the mileage back to what you had before..that about the only forward with this one..unless the instrument panel is faulty..However if the battery is continually going flat then youll need to have the battery checked out.if thats ok then you'll need to test to see what exactly is draining the battery..but as above try the mileage correction/recalibration service if you have one locally and see if they can get it to revert back..disconnecting and reconnecting the battery may not actual work..but you could try it and see if that helps..if not then you'll know what step you need to take next to try and solve this..i do hope this helps
ECU was removed and put in freezer but no change. Is there as battery back up in the dash that holds the true reading?
Not sure the ecu freezing would of worked anyway.usually doing that can really only tell you if the ecu is bad or not by cooling an contracting the board ie:-broken solder/tracks and see if it runs better until of course it heats and expands and the ecu fault crops up again..and that can in a sense confirm a fault with the ecu itself but this wouldnt help in your situation..there should be i believe back up in the cluster itself or BCM..if not then you need to go by previous MOT/Service History so the correct mileage can be recalibrated and this can really only be done by a mileage correction/recalibration service as mentioned before unles the dash panel is actually developed a fault..i do hope this helps further...