exzacklyright wrote:Does the dealership have a different code reader than like autozone?
Nissan dealers, and other mechanics that invest in their business, will have diagnostic tools that enable them to read much more than a single scan code. For example, they can read the values that the sensors are providing to the ECU. Reading the code is a very basic way to solve a problem because it points you in a direction for further research. Using an actual diagnostic tool you can see all the research for you rather than having to get out your multimetre to measure resistance/voltage, etc...
Does this mean the dealer can do everything with a simple scan? No of course not. After my vehicle was rear-ended I started to receive the loose gas cap light, then an error code relating to it. They would not believe me when I told them I can put the gas cap on, and have filled up several times, and insisted on charging the insurance company an hour of labour to tell them "the gas cap is loose". It of course came back, and turns out that the accident caused the evap cannister to have a small crack. It was located right behind the right rear bumper, not so coincidentally the exact point of impact.
To sum it up - yes the dealer/independant shop has tools that can help them do a much more thorough diagnosis that a simple code reader but that does not mean they are always right/can solve every problem on the first try. This is why many people find it easier to start replacing parts themselves because of the high labour cost.