Originally Posted by grim_reaper
P0420 is related to the catalytic convertor &/or O2 sensors.
When you turn the key what actually happens? Does it wind over? Slowly? Fast? Noisy? Quiet?
How's the oil level? How's the coolant?
What do all the spark plugs look like?
Are the camshafts still timed up to the crank?
Does it have fuel pressure?
Does it have spark?
So when I try and start it it wants to buy won't right after it died I started it up again and the was a scraping/grinding I just did a flush and oil change on it within the last month so both are fine spark plugs look good a little black but not oily my dad thinks it might be something to do with timing wether it's that or not it's getting replaced not sure how to check the fuel or compression but I'll figure it out I'm determine to fix my car and I appreciate the advice any help is greatly asked for