I have had my vehicle to 3 different dealers to diagnose the problem for a fix. No error codes are being stored is one issue and the service engine light is not on. here is what happens, while drving at any speed, the truck seems to feel like it stalls. All indicator dash lights come on, (service engine, ABS, etc as well as park assist). After a brief second or so, all clears and truck resumes. I was told it is going into limp mode briefly but they cannot diagnose since there are no codes and the service engne light does not stay on. Acts like a huge hiccup. Lose everything. At high speeds, the truck will just roll through it and only the dash lights alert you it happened. Slower speeds can really be felt. I am afraid this could become a safety issue. Does anyone have any idea where to begin. I would think someone would know at the places I have been. Come back when the light stays on is what I am told. Maybe someone here can provide some input....please

SOURCE: Loud air intake engine noise on startup

I would guess it is the electronic fan clutch. It will cause the fan to run too fast (very loud) and the light will come on sometimes.

SOURCE: 2002 GMC 2500HD 8.1L

Sounds like the cam positioning sensor. I have a 2002 GMC 2500HD 8.1L and this happened to me. Hope this helps.

SOURCE: 2003 Sonoma SLS 6 cylinder 4.3L ABS issue

I WOULD NOT KEEP DRIVING IT.WHEN ABS LIGHTS AND BRAKE LIGHTS COME ON.YOU HAVE BRAKE FAILURE. TOW IT TO DEALERSHIP HAVE IT SERVICE.AND CHECK THE ABS BRAKES SYSTEM .BECAUSE ABS BRAKE SYSTEM IS NOT A HOME FIX.BECAUSE THE ABS HYDRAULIC MODULATOR UNIT HAS LOWER FROM HOME POSITION .IN ORDER TO MOVE THE MASTER CYLINDER FROM UNIT.YOU NEED A TECH 2 SCANNER TO DO THE JOB.TO GET ABS BRAKES TO BLEED RIGHT BEST TO GET THEM PRESSURE BLEED INSTEAD OF MANUAL BLEEDING GET LESS AIR IN SYSTEM.THAT WHY SEE DEALER SHIP HAS THE THINGS TO DO THE JOB.

SOURCE: 2004 denali check engine light stays on

There is no p01001, it's either p0100, or p0101.
Anyway, it's the mass air flow sensor that's bad. The p0171 and p0174 is a lean condition on bank 1 and bank 2, which are the oxygen sensors. Change the mass air flow sensor and that should take care of the p0171 and 74 codes.
The mass air flow sensor can cause the 02 sensors to read lean.
The u1301, is a class 2 circuit short to battery. That, you have to test wires to find with a voltmeter/continuity tester.
I would try and find that short before changing the flow sensor, you don't need the new one shorting out, they are not that cheap.

SOURCE: 2004 envoy service engine light stays on. Told

Our mechanic said we need to replace the computer! The cost will be $1,000.