the car is a 2k4 with the downstreep o2 in the exhaust i throw a p0420 (catalyst below efficency threshold) with the o2 out of the exhaust i throw a p0136 (o2 circuit malfuntion). I cleared the p0420 before and sometimes its gone for a week before it comes back, but now I'm sick of the engine light. I searched all over the internet and these codes rarely coincide w/each other. Please Help.
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4 Cams...32 Valves...5 Liters...This Could Get Fun!
ditto. means your cats not working properly.
