P 3400
 

Bought yesterday 100 miles later this code. Can't see any oil leak. Oil change recently done and filled proper level.2020 cx5 with 88000 miles. Touring edition i think. No oil on ground or in engine bay. Car seems to run really good

Welcome to the forum

when you ask a service related question you really need to include basic information:


Year
Miles
Last service down and date and miles
Other noticed running conditions not normally observed?

DTCs are only a starting point for a qualified or experienced individual to start a tree of service elimination.

Welcome to the forum.
P3400 code is a CDS (cylinder deactivation system) error for bank 1.
It has nothing to do with oil.

Not necessarily....

How many times have we read and in my case had to service a problem caused by another shop , dealership or DIY damage another part while doing something as simple as an oil and filter service. :p