today i plugged in my neighbors turbo link into my car and i got code 13-O2 sensor, code 15-low CTS volts, code 23-low MAT sensor volt, and code 44- exhaust lean. after this i went and got a new O2 sensor from pep boys and put it in and all the old codes came up and even a new one, code ??-EST(Electronic Spark Timing). my fan shuts off as soon as i turn my car off so i think the fan delay relay is gone and kirbans performance book said that a bad fan relay can set a CTS code and i just installed a new autometer water temp guage so maybe thats what is wrong. when looking at the computer screen on the turbo link the readings fluctuate a lot like the O2 will go from 65 to 726 and stuff like that so my neighbor thinks my ECM might be on its way out. would any of these codes cause a 10 psi boost situation? can anyone help me out in figuring out these codes and how to get rid of them?