'97 Cherokee Sport Engine Code 45

I have recently purchased a 1997 Jeep Cherokee Sport. The Check Engine
Light has come on twice in the last 3 weeks. Using the "Turn Ignition
Key 3 Times" tool, I get error codes;

12, 45, 17 and 55

I have found multiple posts on the web as to what the codes are, but
none of them say what 45 is.
Can someone enlighten me?


Thanks

Mike