For those doing performance mods (including the K&N Filter) it is of great benefit to do a quick ECU reset which will force the ECU to learn the new settings faster than waiting for it to self adjust over 2-3 days.
The ECU Reset process has been detailed on the Australian X-Trail Forum HERE
P.S. Marc, you may wish to add this to the "How To" list if you like.
I was just about to complain about my gas mileage getting worse when i stumbled upon this thread. It reminded me that I had only cleaned my air filter once in 2 yrs. After cleaning the filter and re-oiling it I reset the ECU following the instructions on the Aussie X trail forum. My mileage is now back to the way it was.
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