I turned off EGR Valve and the Diagnostic codes for it.
1 Diagnostic code gets set .... Exhaust Gas Recirculation Sensor A Circuit Low
The OS is changed ? PCM hardware bad ?

Should I flash calibration data and OS ?
I just do calibration data only.


P01, ECM, GM Gen3 V8, 4.3L V6
Operating System 12208322
Engine 9357826
Engine Diagnostic 16264001


2001 GMC 2500HD 6.0L, 4L80e, 3.78RR 11.5' Ring Gear Locker, 1 Ton Rear Leaf Springs, 856,000+ Miles