Will a Catback exhaust cause check engine light?
Will a Catback exhaust cause check engine light? If you replace ANY of those stock cat pipes with either "offroad" (no cat) versions, or with aftermarket catalytic converters, you MAY get the P0420 "Check Engine" light (CEL). Even downpipes with aftermarket catalytic converters MAY result in the CEL! Do test pipes cause check engine light? Jordan, most test pipes/ high flow cats come with o2 sensors, hence they will not throw check engine lights and may infact pass emissions testing. Why do I need a cat back exhaust system for my F-150? A cat-back exhaust system for your F-150 is...