P0301 localizes misfire to Santa Fe cylinder 1 but does not identify the coil. Confirm cylinder 1 on the exact inline-four or V6 diagram, preserve cold/load counts, inspect the labeled plug and make one controlled ignition comparison. If it stays, test injector contribution and compression/leak-down. Production-bounded 2021–2022 non-turbo 2.5L Santa Fe vehicles may match Hyundai's GDI injector bulletin; other engines do not inherit its all-four-injector repair.
Match the symptom
Select the closest observation. The result changes the first test; it does not name a part to replace.
Stop loading.
What can set P0301—and how to separate it
The order below is evidence-driven, not a universal probability ranking. Vehicle year, repair history, companion codes and the operating condition in freeze frame change where diagnosis should begin.
| Possible cause | Evidence that supports it | First useful test |
|---|---|---|
| Cylinder 1 plug fouled/worn/cracked | Abnormal deposit/gap | Labelled plug |
| Ignition component/circuit | Controlled test follows | Targeted ignition test |
| Injector fault | Count stays/contribution differs | Balance/command |
| Compression/valvetrain | Low mechanical contribution | Compression/leak-down |
| Cam/crank timing fault | P0016/P0340/sync data | Correlation diagnosis |
Keep cylinder evidence intact
Label plug 1 and compare gap, deposits, cracks and fuel wetness with a neighbor. Move one known-good ignition component only when the engine hardware permits.
If the count stays on cylinder 1, return the known-good part. More swapping does not test injection or sealing.
Test fuel and mechanical contribution
Use engine-specific injector balance and pressure data, with high-pressure safety on GDI. A leaking injector can wet the plug and dilute oil.
Measure compression and leak-down under comparable temperature. Valve sealing, valvetrain or timing faults can keep the count local.
Respect the injector bulletin boundary
Verify production date and VIN origin before using the 2.5L GDI kit instruction. The bulletin is not for turbo, V6, hybrid or another year simply because P0301 matches.
Confirm no cylinder 1 counts under original safe conditions and no pending P0301.
Save these scan-data clues
Freeze frame is a snapshot of conditions when the PCM matured the fault. It can distinguish an idle-only problem from a load, cold-start or monitor-completion problem. Clearing first throws that context away.
- Exact VIN, platform, model year and engine sales code
- All confirmed, pending and permanent companion codes
- RPM, load, coolant temperature and vehicle speed
- Relevant commanded and actual scan data
- Recent service, repairs and symptom conditions
- Manufacturer bulletin and current software/VIN status
A practical diagnostic workflow
- 01Identify engine and cylinder 1
Use exact diagram.
- 02Preserve condition
Capture cold/load counters.
- 03Inspect plug
Keep labeled.
- 04Test ignition once
Watch whether count moves.
- 05Test injector and sealing
If it stays.
- 06Check timing companions
Do not ignore correlation.
- 07Retest
Verify original conditions.
Do not replace the most commonly named component from P0301 alone. Confirm the exact engine, preserve evidence and complete the manufacturer test sequence before ordering parts.
Why the model year changes the test
Santa Fe diagnostics span CM, Santa Fe Sport DM/AN, XL three-row and newer TM/MX5 generations with inline-four, turbo, V6, hybrid and plug-in powertrains. MPI, GDI, CVVT, intake-runner hardware, catalyst banks, EVAP routing and P1326 campaign coverage differ. Confirm VIN, model year, Santa Fe versus Santa Fe Sport/XL, engine code, drivetrain, production date and ECM ROM before applying a bulletin or diagram.
- Inline-four and V6 cylinder numbering differs.
- 25-FL-001H is limited to selected 2021–2022 TMA 2.5L non-turbo vehicles.
- GDI fuel systems require depressurization and one-time parts.
- P0017/P0014 companions raise timing priority.
P0301 FAQ
Is P0301 always a coil?+
No.
Can I drive?+
Not with flashing MIL or shaking.
Can I swap coils?+
Yes when engine hardware supports it.
What if it stays?+
Test injector and compression.
Can valves cause it?+
Yes.
Why check timing codes?+
They may explain the misfire.
Should I clear first?+
No.
What confirms repair?+
No cylinder 1 counts under original conditions.
Ford diagnostic references
These documents explain Ford monitor operation. Exact pinpoint tests, connector views and specifications must be selected for the truck's VIN and model year in current service information.
01Hyundai TSB 25-FL-001H — selected Santa Fe 2.5L GDI misfireProduction-bounded 2021–2022 Santa Fe TMA non-turbo 2.5L branch for P0300–P0304 and all-four GDI injector replacement↗02Hyundai TechInfoOfficial VIN-, engine- and model-year-specific shop-manual and GDS procedures↗03Hyundai manuals and warranty informationOfficial model-year owner manuals, warnings and maintenance information↗