CTS repeated code

my check engine light is on and i checked the code. i get 12, 21, 22, 22, and 55 (i triple checked). Has anybody else had the same code come up twice? i looked up the 22 code and it's the coolant temp sensor. i replaced it and i get the same. i did notice just now though that my manual says to replace it once the engine cools off (5 hours). i replaced it with the engine at operating temperature. is that a problem? is there a possibility that my computer is bad? i also replaced the oxygen sensor and i still get that code (21). Anybody? It's a 93 xj manual trans.

Disconnect the battery to clear the codes, or you can wait another 50 starts and the codes will clear themselves. Autozone or any of the places that pull codes for free can clear the codes as well. Shouldn't matter if the engine is warm when you replace the CTS. I think it says that so you don't spray yourself with hot coolant.