P0420 Jeep -

Question

2007 jeep wrangler 3.8L Im getting a P0301 cylinder 1 misfire with the P0420. Please any help will be greatly appreciated Thanks Chris

Answer 1

P0301 Misfire number one cylinder

P0420 Catalyst below effeficeny Bank 1

Misfire if allowed to run long enough will ruin the catalytic convertor,just having the misfire can set P0420. When a misifre occurs it can be from a ignition problem, or a fuel injector problem to a mechanical problem. check the sparkplug and note its condition , if it is wet with fuel a compression test should be performed, and should not be less than 100 psi and no more than 25 percent form other cylinder, you can also remove the fuel injector of the number 1 cylinder and swp it out with a known working cylinder, clear the code and if  the misfire moves you would know that the fuel injector would be the problem