Altima P1800/P0420 do both the VIAS and CAT need to be replaced and that will solve issue?

Question

What are the proper troubleshooting steps that the dealer/repair shop will need to do to ensure that we are not just throwing parts to fix the P1800/P0420 codes? Nissan Altima 155,000 miles 3.5 SE manual transmission.

Answer 1

What year is your Nissan Altima?

P0420 Nissan Code - Catalyst System Efficiency Below Threshold Bank 1
Read more: https://www.autocodes.com/p0420_nissan.html

P1800 Nissan Code - Variable Intake Air System Control Solenoid Valve Circuit
Read more: https://www.autocodes.com/p1800_nissan.html

The information is too long to post here. We suggest registering on Nissanhelp.com and download the "Engine Control" section of the service manual, it's free.

http://x.nissanhelp.com/forums/Knowledgebase.html?catid=26