ok, code 12 is the beginning code, 23 is for intake air temp sensor, if this has been disconnected for any reason and the key was turned on, this may be the reason for that code. The 55 is end sequence... At this time there is no code 15 so the speed sensor is operating normally. Is there any speedometer repair shops in your area? If so, that may be the best chance of getting this fixed.
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