55 code comes up when you turn key on and off

Well there are no single digit codes.
Code 12 means the battery power has been lost within the past 50 key starts.
Code 55 means you have reached the end of the code test.

55 Completion of diagnostic code display

It just says that it completed the diagnostic check (get one everytime you start your vehicle)

Turn the key to run then off, back to run, then off, then to run and leave it on. The check engine light will be on and will then go off and then on again according to the codes the engine controler happens to have in it. If the check engine light was on when you stopped the car, then there is at least one code in the controler. The light will blink the codes like this.
Cycle the key three times and leave on on the third time. light on for about 3-4 seconds then goes out for about 2 seconds and then blinks one time and goes out for 3 seconds this is for the no.1. Then the light blinks 3 times and goes out for about 3-4 seconds. You have the code 13. You could have a whole string of codes in the controler memory. It could be something like this. key cycled 3 times, light on for 3-4 seconds, then blinks 1 time, pause, 3 times, longer pause, 2 times ,pause 4 times, longer pause, then 5 times, pause 5 times the goes out.
This is code ; 13,24, 55. code 55 isn't really a code. It just tells you it's the end of any codes the controller has.
If you disconnect the battery and hook it back, you will have code 13 which simply mean 'battery disconnect'. It will errace it's self after several starts if it's not disconnected again. If you cycle the key and you get 55, this means there are no codes recorded at this time.
You will allways get 55 when checking for codes wheather there are fault codes or not. The light on for a few second before the codes start flashing is only a bulb check. Some codes like 13 will not turn the check engine on, but but will leave a code for diagnostic purposes only. If you have the check engine light on and accellerate and the light begains to blink, then the controller is telling you that you have an engine miss and are running the chance of burning out you're catalatic converter if you continue driving. Sometimes its advised to disconnect the battery after you have recorded the codes.
This will erase all codes that are present but were generated by conditions that aren't pertanent to the present condition. and then the codes that come back are the real ones to address.
This link: http://minimopar.knizefamily.net/fault/index.html
Contains the entire list of Chrysler Engine Error Codes.

Hello Steven.

That reads code 12 and 55.

12 is power disconnected to computer in the last 50 key starts.

And 55 is end of service codes.

Neither one of those codes will turn on the check engine light.
If the power is interrupted to the computer when you turn off the key the codes stored will be erased.
So the code has been erased and no longer stored or you have a key off power supply issue to the computer.

If you need further assistance on this, ask me here.
Thank you for using FixYa.

KL

The numbers are grouped in twos.
12 Memory standby power lost (this means that you must have disconnected your battery. It will turn off in the next 50 key cycles.
34 Speed control vacuum or vent control solenoid circuits.
32 EGR system
55 end of codes it will always flash 55 informing you that it is finished
Hope this helps give feedback and good luck FixYa

code 55 is Completion of fault code display on Malfunction Indicator Lamp.

Code 12 is: Battery input to PCM disconnected during last 50 key starts.

Code 55 indicates end of codes. If you are retrieving codes, code 55 will indicated that you have reached the end of the code list. Code 55 will always be reported regardless of if there is another code to report or not. If you don’t receive a code 55 when retrieving codes, the power limited light may be burned out (or you may not have done the code checking procedure correctly). Good work and keep me posted for any other questions you may have.

You need to find out what code is in the computer. Either have it scanned or flip the key on off on off on off on.(three times) The check engine light will flash to tell you the codes. ie 2 long flashes, followed by two short flashes would be code 22. It will repeat each code three times. It will start with code 12 and end with code 55. Code 12 is start code and 55 is end code. What ever codes come up between these codes, write them down and post.

did you get the codes by doing the "key dance"(on,off,on,off,on) ?

if so, it almost always flashes a 12 and 55. here is what they mean.

12 - direct power input to the PCM has been disconnected within the last 50 key-on cycles

55 - End of error messages

code 12 is start

13** No difference recognized between the engine MAP reading and the barometric (atmosphereic) pressure reading at start-up

Code 55 is end so 13 is all you need , basically your map isnt working
its an easy fix if thats all , take one off , put new one on