splitnails wrote: ↑

Mon Dec 25, 2023 10:57 pm

If I get the full headers/exhaust from PPE with high flow cats will that fix my P0420 code? Thanks!

It should, as the P0420 is a low efficiency threshold DTC...just means your cat is not cleaning the exhaust to the 92% threshold. The M56 is notorious for throwing this code after it reaches higher mileage. If you decide to go this route, it is recommended that you also tune the car since you are radically changing the stock set up.

As stated above make sure you know what's causing the p0420 code 1st, make sure no other stored codes too. Sometimes could just be a o2 sensor, bad spark plug, headgasket, etc etc. Don't assume all p0420 is just the cat.
You'll be spending thousands on a new exhaust. Around 2k on just the headers and near that much more for install if not doing yourself