i bought a yukon from a guy and its got the 5.3 and from the boost guage looks like about 6 psi is what its set on. my problem is the engine light keeps coming on and puts out P0404 some egr performance code. it also has a whipple tune on it i have the handheld tuner. does anyone know how to solve this problem or if i can retune it to not throw a code?