Chrysler Repair: Key-obtained Fault Codes 12, 43, cable clamps, spark coil

Question
What does key code 1-2-4-3 mean

Answer
Hi Verna,
The 12 code means that sometime in the past 50-100 uses of the car the battery was disconnected or the voltage supply to the engine controller was disconnected (loose connection?). It is not very relevant accept in the case if the car simply dies which would prompt one to check the battery cable clamps.
The 43 means that the primary winding of the spark coil(s) is not responding as expected as far as the current it is drawing is concerned. It would be noted as a loss of power or a misfire. Other than to check the wiring plug begin the coil and the engine controller the only other explanation is a weak/failing spark coil.
Otherwise I would not be too concerned about these codes. If you are, let me know the year, engine and model of car you have. I assume that you have a pre-97 car and that it doesn't have a turbo charger on the engine.
Roland