Pathfinder ECM Reprog after P0455 Code?

[rich201]

Hi, I'm looking for some advice please. Before I ask my question i need to give you some context.

I have a 2005 Nissan Pathfinder LE 2WD with 133000 miles. 5 days ago I had a SES light come on. I took the car to my local shop who has handled all of my servicing since I bought the car 8 months ago apart from 1 issue I had which I took to the dealers (after the shop advised me to) which resulted in $2500 of work some of which I am unsure it needed.

The local shop pulled the code P0455, carried out a smoke check, found that the Evap Vent Solenoid Assembly required replacing, replaced it with a genuine Nissan part bought from the dealer and everything was fine.

15 miles after leaving the shop I had a recurrence of the SES light and having gone back to the shop they pulled the same P0455 code. The mechanic informed me that the next step in the repair as shown on his SnapOn ModusUltra Diagnostics was to have the ECM reprogrammed by a dealer. I took the car (reluctantly) to the dealer.

The dealers "Customer Relations" guy informed me that the shop may not have carried out the correct test or that the code may have been latched on and not cleared correctly and that they would need to do their own diagnostics. He also informed me that the "reprogramming the ECM option" is usually when a mechanic doesn't know what to do next and wants to "move the customer on". Given that I have a reasonable relationship with my local shop this made me nervous as it seems unlike them to do such a thing, indeed they have an excellent reputation for good work. He also informed me that he could see no reason why an ECM reprogram would fix the issue.

My question is this; Is there a genuine circumstance that following the replacement of the Evap Vent Solenoid Assembly, a reprogram of the ECM could be necessary and would fix the problem of the recurring P0455 code? Does the dealer have access to more information on a fault by carrying out their own diagnostics than the local shop utilising the SnapOn diagnostic tool?