98 5oh XLT
Well-Known Member
- Joined
- September 12, 2010
- Messages
- 167
- Reaction score
- 2
- City, State
- Clackamas, Oregon
- Year, Model & Trim Level
- 98 XLT AWD X "Loki"
Got a constant check engine light on, its always p0420, Book says "catalyst system efficiency below threshold (Bank 1)". What exactly does this mean and does this mean i gotta replace a cat? Sensor? EGR valve? Cheaper the better (i think we all pray by this motto! LOL) Thanks again for your help 
