I went to buy an 07 Nissan Xterra SE and it had a Check engine light for a cylinder 1 misfire. So the guy took it to his buddies mechanic shop, and they replaced the one spark plug and coil. Retest drove it and seemed fine, so I bought the car and started driving home.
Within a 30 minute drive the car was driving rough. The engine felt as if it might have been rumbling or shaking a bit so I pulled over. I had a Service engine soon light on and had it coded, the code I got was p0420 catalyst efficiency below threshold. After looking things up I do believe this happens a lot for this car and year - just the Catalytic converter going out.
So the guy took the car back to the mechanic and the first go round when they took the intake manifold off to get to cylinder 1, they might not have put it back on correctly and I feel cold air coming out. So I believe there is a vacuum leak...
It was at the shop and the guy told me that he bought a new Intake manifold for them to put on but I found out he lied and when I spoke to the mechanic he said he never received it so all they did was replace the brand new coil pack on the cylinder 1 spark plug and it supposedly fixed it and made the light go off - until I drove it home and the light came back on.
It doesn't seem to be running rough but I'm not sure if the engine only have 1 new plug and coil is throwing off the balance and making the code for the catalytic converter show up or if its due to the catalytic converter going bad or if its the intake manifold having a vacuum leak. Any thoughts?