Some Mazda vehicles (2012-2013 Mazda3 SKYACTIV, 2014-2023 Mazda3, 2014-2021 Mazda6, 2016-2019 CX-3, 2013-2023 CX-5, 2016 CX-9, and 2016-2022 MX-5) may experience a check engine light on with DTC P0171 (fuel trim too lean) and possibly P030X (misfire).
Inspect the airbox/air filter for proper fitment. Inspect the MAF for correct operation. Inspect the A/F sensor for correct operation and inspect the fuel trims during normal engine idle.
If fuel trims are normal after the aforementioned inspections/repairs, the repair is complete. If fuel trims are abnormal, replace the fuel injectors and verify that the fuel trims have been corrected. Note: P0171 will be set while the engine is idling or if the vehicle is driven and the fuel feedback correction amount reaches the upper limit (25% or more) for 20 seconds or more.
