P0171 GMC -

Question

Step on brake pedal and truck dies I'm about done with trucks and cars and about to use the public transportation f**

Answer 1

HI there,

This code is for a lean fuel mixture on bank 1. Since it's happening when you step on the brake, check for vacuum leaks. It's possible there is a leak at the brake booster or somewhere along the intake. This could cause the stalling when you step on the brakes since they are vacuum operated.