I got a 2000 trans am, a4, 144k, long tubes y pipe, if any of that matters lol. It threw this code and im not sure if it did before i installed the headers but im sure it did. Car pulls hard on the street like short burst but ran disappointing times in the 1/4 at the track. 15.3 trapping 92. Trying to trace the issue as to why it ran so slow and this is something i’m thinking might have a cause. Any help as to why its throwing this code or why it ran so slow? Thanks

 

That’s an exhaust gas recirculation code. Was the EGR valve “deleted” when the headers were put on?

 

Sounds like a visit to your favorite tuner is in order

 

A P0405 usually points to a bad EGR valve or clogged passages, especially after header installs. That could explain the sluggish track times, EGR issues mess with low end torque. Check the valve first and clean the tubes if they're gunked up.

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