Some 2016-2022 Mazda MX-5 (Miata) vehicles may experience the check engine light on, with DTC P0171 (fuel trim too lean) and possibly P030X (misfire).
Inspect the airbox/filter for proper fitment and repair if needed. Inspect the MAF for correct operation and repair if needed. Inspect the A/F sensor for correct operation and repair if needed. Inspect the fuel trims during normal engine idle condition. If fuel trims are normal, repair is complete. If fuel trims are abnormal, continue with the repair procedure as follows:
- Replace the fuel injectors
- Verify that fuel trims have been corrected.