P0301 means excessive misfire on cylinder 1; it does not prove coil failure. Locate cylinder 1 from the exact J35 diagram, save cold/load counts and inspect plug 1 in context. Make one controlled coil swap; if the count stays, test injector delivery and compression/leak-down. Honda Bulletin 26-001, issued February 2026, covers VIN-eligible 2013–2017 Odyssey P0301–P0304 cases involving ring wear/sticking and oil-fouled plugs. Its sequence may require software, plugs, ring cleaning/replacement or block inspection. Eligibility and diagnosis—not the code alone—control the remedy.
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 |
|---|---|---|
| Plug 1 fouled/worn/cracked | Abnormal deposit/gap | Labelled plug comparison |
| Coil/boot/connector | Swap follows or circuit fails | One swap/loaded test |
| Injector fault | Count stays/contribution differs | Balance/leak/command |
| Compression/valve/timing | Low mechanical contribution | Compression/leak-down |
| 26-001 ring condition | VIN/year/code/fouling/inspection match | Bulletin workflow |
One swap answers one question
Move coil 1 to a known cylinder and monitor counts.
If it stays, stop swapping.
Plug evidence matters to 26-001
Oil carbon, fuel wetness and coolant cleaning differ.
Keep plugs labeled.
Warranty language has boundaries
The February 2026 bulletin requires VIN inquiry and diagnosis.
Its time/mileage wording is not permanent universal coverage.
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.
- Cylinder 1/all counters
- RPM/load/ECT/speed
- Bank trims/fuel pressure
- Plug 1/neighbor deposits
- Compression/leak-down
- VIN/software/status
A practical diagnostic workflow
- 01Locate cylinder 1
Use exact J35 diagram.
- 02Preserve condition
Capture cold/load counts.
- 03Inspect plug
Photograph and retain.
- 04One coil swap
Watch if count moves.
- 05Test injector/sealing
If it stays, prove fuel/mechanical.
- 06Apply bulletin gates
Verify VIN and diagnosis.
- 07Retest
Confirm original condition without flashing.
Do not replace six coils or promise ring repair from P0301. A new plug can temporarily hide injector, oil or compression trouble.
Why the model year changes the test
Odyssey diagnostics span several J35 V6 generations, port and direct injection, VCM cylinder deactivation, conventional and newer EVAP hardware, plus six cylinder-specific misfire codes and two catalyst banks. Confirm VIN, model year, engine/calibration, emissions label and current Honda warranty/campaign status. Do not transfer four-cylinder Accord, Civic or CR-V VTEC bulletins to this J35-powered minivan.
- 26-001 applies to VIN-eligible 2013–2017 Odyssey.
- It states a 10-year/150,000-mile extension; actual VIN/date status controls.
- 2018–2019 injector extension is a different program.
- Correct cylinder/bank identification is essential.
P0301 FAQ
Always coil?+
No; plug, injector, wiring and mechanical causes exist.
Can I drive?+
Not with flashing MIL/shaking.
Does every 2013–2017 qualify?+
No; VIN and diagnosis control.
Can I swap coils?+
Yes, once, while monitoring counts.
What if it stays?+
Test injector and compression.
Should I clear first?+
No; preserve data.
Can rings cause it?+
Yes in the bulletin's verified condition.
What confirms repair?+
No cylinder 1 count 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.
01Honda Service Bulletin 26-001 — 2013–2017 Odyssey P0301–P0304February 2026 warranty extension; VIN inquiry and full diagnosis required before plugs, software, ring or block repair↗02Honda ServiceExpressHonda VIN-specific diagnostics, wiring, bulletins and campaign status↗03Honda Owners — Odyssey manualsOfficial model-year warnings, maintenance and operating information↗