Thread: Random PO420 Code

When my cat was going bad at around 116K miles, I started to notice loss of power that got progressively worse until I could barely make it up hills. Eventually it got so bad that when I looked under the hood in the dark, my rear exhaust manifold was glowing red. That's when I knew it was really time to change it. Luckily, my year GP GT was still under the 120K miles warranty and the dealer replaced it for free. After changing it, my car felt like a new car once again.