P0171 after in tank filter change

I have had the in tank filter changed and the trans axle fluid changed. The Mechanic at the dealer said he agreed with my (and Prius chat's officionados) that the "life time" of the fluid is probably 160000Kms. As I drove the car away it misfired and the check engine light appeared. My Ultra Gauge presented the P0171 dtc," too lean".

I took it back immeadiately and they dismantled the fuel tank again and found that the O ring on the spigot from the pump had been assembled before the spacer rather than after and there fore the fuel was escaping back into the tank. Problem solved.

The Dealer gave me a loan car during the original service and for the overnight wait for them to solve the P0171.

Well the lesson from this P0171 is that it's not always the MAF and fuel pressure drop for any reason can cause it. (My first thread and on the new Prius Chat!!)