is it really the converter? 2005 Nissan Titan

Question

i have a 05 nissan titan, and went to take my emissions test and I failed it with the code of P0420.  I had already taken this test last year, i had got the same code then and I had my converters replaced. Im not a car genius but its hard for me to believe that my converter would go bad in a year, and im trying to see if there are any other explanations to this. i did do some reasearch and some people say that i need a new O2 sensor but im still a bit iffy about it.

Answer 1

Hi there,

If you used aftermarket parts, it's possible the converter is bad again. Also, the rear O2 sensor is a real possibility for the cause of the problem. I have also seen it caused by leaking exhaust manifold and poorly tuned engine. Sometimes even the fuel additives the companies use can bring on the code as well.