Corolla AE100 RPM Counter

Bad temp sensor is most likely the problem.

Repair your vehicle right away. Just click on the link I attach
http://www.reliable-store.com/products/1994-toyota-corolla-sprinter-ae100-owners-manual
http://www.reliable-store.com/products/1994-toyota-corolla-sprinter-ae100-owners-manual

Macsry2k answer makes the the most trouble shooting sense. Problem is definitely electric. Since the alternator is where the RPM reading comes from, this is the best place to start. Good luck!

I think yoy have an internal transmission issue that will require and overhaul to correct.

Hi

I am just wondering if someone could advise on the problem that car are consuming too much gas/fuel.

Does the engine temperature getting up to normal range? If the thermostat is removed, or stuck open the engine temperature sensor will not allow the transmission to go into overdrive since it thinks the car is too cold

The Code 12 on your Corolla it refers to a problem with the Rpm signal from the distributor, I recommend you to replace the distributor, make sure that is complete with the coil and igniter installed, you can save quite a bit of money by getting one from a salvage yard or an aftermarket unit from a local auto supply store !

I am not familiar with this engine. But, if the alternator, PAS and AC are being driven by the same belt, then its possible that the belt is too slack, have you checked the belt tension ? That would be my first step. Hope that helps

My Corolla's (AE100) RPM Counter does not read correctly

Don't think there's anything wrong with it. That's pretty normal for mine. If it's unusual behaviour for your car, check your coolant level. I almost ran mine dry last year and found in the days leading up to it that my idle revs were sitting around 2000 once the car heated up. If it turns out to be that I can give you some real handy tips for changing your coolant and flushing all the junk out. Much cheaper than a mechanic and good if you have a spare hour.