P0420 Buick -my car surges while driving. The cat converter is not discolored.

Question

The car has not just shut off,, however, it has died immediately after cranking but only when cold.

Answer 1

Hi there,

Even though it's not discolored the converter can be the problem. Also, if it's plugging up or is plugged up the car is going to surge and possibly stall and be low on power. I would start by removing the O2 sensor before the converter. If the car will start and run, the converter is plugge and will need to be replaced.