Surreal Development’s General Motors Emissions Diagnostic Guide This document is intended to be supplementary guidance based on Surreal Development’s own knowledge of GM diesel engines. This document is made to be a reference in tandem with OEM service manuals and is not made to be a replacemen...
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The guide is made to focus on fast diagnostics to get vehicles back on the road as fast as possible. It focuses more on solutions rather than long diagnostics. If we apply a 60-30-10 rule. This guide can literally fix 90% of emission problems which I have seen.
It will not tell you what bolt to turn. Its focus is purely on diagnosing.
I also added a section people can use on old cars to see if they have been tuned.
PS for something like trifecta who overwrite the CVN it will.
1. Have more than 1 entry (has been flashed since factory)
2. Probably have more than 1 counts.
I have been incorporating these steps with some dealerships around here as well as some emissions stations in other states. It works very well. And I would never buy a used vehicle without doing this.