I have codes 171,54 on my 2005 trailblazer it has 242794 miles on it. Over the past year I have tested cleaned and/or replaced everything to do with emissions that I can think of! By the way it idles I have a vacuum leak but can't find it. The idle doesn't always run high. The normal idle is around 600rpms but sometimes it idles at 1500 and 1000 rpms it's not consistent. Fuel pressure is 56psi and Haynes says 50/57 psi. The 54 code has to do with o2 sensor but it is brand new about 4 months ago. I ended up changing cat out and it was empty only a shell. At moment I'm at a loss where to look next! Thanks if you have any suggestions.
For codes 171 and 54, do you mean P0171 and P0054?
Well start by finding the vacuum leaks. Have somebody hook up a smoke machine to find it. It could be intake manifold could be lots of things and that can cause all kinds of codes. Always start with the obvious things first. Otherwise you can get really complex
