Almost have a 99' Blazer...
 

Can someone explain what the code PO147B indicates and perhaps the required fix options?
Also, why would there be a fluid leak from the tranny output gasket on a recently rebuilt transmission? Is this a common problem with Blazers?

out gaskets seem to leak on almost every vehicle i see. i have a few trucks and even after replacing them they seem to instantly leak no idea why so i just ignore it.

P0147 Heated Oxygen Sensor (Bank 1 Sensor 3) Heater Circuit Malfunction
Possible CausesSetting Conditions

• HO2S heater ground circuit is open or has high resistance
• HO2S heater power circuit is open (test O2S fuse in fuse block)
• HO2S heater element has failed
• PCM has failed

PCM failed??
 

Ok. What is a PCM? How can it fail?