I was looking through the manual, but it did not seem to have any with the label EXH.

 

Not seeing it either

https://fuse-box.info/chevrolet/chev...uses-and-relay

 

#33 underhood.

 

Ah, the emissions fuse#33

 

Pulled, checked, and didn't notice anything strange with it. I swapped it for the spare fuse that is in the box lid and started car. Same Check Engine Light.

 

Refresh my memory, what is that code?

 

P0131 and P0420. They seem to be the first Exhaust sensor and then the catalytic system. From searching it seems the first code may cause the second code

 

Precisely

Take care of the P0131 code and most likely you’ll fix the second code.

 

p0131 is low voltage to O2 sensor #1. That means check the wires/connectors, if they are all good replace the #1 sensor.

It means the voltage is less than 50 mV; in other words: disconnected from voltage supply. Not unusual for the wires to get dislodged and burned on the exhaust pipe, or water in the connector.