Let's say I have 96 159 4.9 6 cl with code p0171 say I looked and fixed vac leaks cleaned MAF then changed 02sensor in bank 1 and have battery disconnected after work is done do I have to use one of those computer Thingys like they used to tell me the code to clear code and check engine lite or will it do it on it's own??

 

Disconnecting the battery for 20-30 minutes will typically clear all stored codes.