I have a 2013 Kia Soul with a p0420 code I’ve had on and off since October. I’ve replaced all the sensors, run the cataclean but it’s still coming back so I’m pretty sure it’s the cat. Lately I’ve had trouble starting the car intermittently and was wondering if a clogged cat could also cause that? The car has about 126000 miles on it but also has a new engine from the big recall that’s not even two years old. The mechanic can’t get the problem to repeat unfortunately. In my mind I think that could be possible if the car is trying to take in air but there’s such a large clog that it can’t vent out. Am I thinking correctly or way out in left field?
was wondering if a clogged cat could also cause that
to test your theory, remove the upstream O2 sensor.
The upstream sensor is actually brand new installed only a month ago. The starting problems do predate the replacement
I think the idea is that if your catalytic converter is clogged, removing the upstream O2 sensor will relieve some of the pressure and possibly permit the engine to run. Also you can use a suitable gauge to check for backpressure.
Chuck is correct. That's why I said remove, not replace.