P1635 + P1271 Chevrolet

Question

Both of these faults come up on my blazer. I did an oil change and tire rotation and was driving my vehicle home when the vehicle went into limp mode and had a hard time getting up a hill. It was the first snow fall of the year too. both codes popped up at almost the same time. Wondering if they are related. I found a lot of different scenarios of what it could be and that's a lot of different things to try. Ex: change TPP, check EGR, MAP, TPS, change cooling fan clutch. I don't know how to check any of these and I don't want to replace random parts. And I can't afford to take it to a shop. Can anyone dumb this down for me

Answer 1

P1635 5 volts reference circuit

P1271 Accelerator pedal position sensor 1-2 correlation

If you set a P1271 you would also set a P1635. The only code that need to be looked into is P1635. What this is a 5 volts reference to certain sensor such as Throttle position sensor 1, Accelerator pedal position sensor 2, ,  A/C pressure sensor. , Fuel tank pressure sensor , oil pressure sensor. if one of these sensor short you would set a P1635 this would also set a P1271.