P0300 (generic)
Random/Multiple Cylinder Misfire Detected
System: Powertrain · Ignition / Misfire
Severity: severe · Inspection: often fails
Description
The engine is misfiring across multiple cylinders. Most common causes: worn spark plugs, failing ignition coils, vacuum leak, low fuel pressure, bad fuel injectors, low compression. Start by checking plugs and coils.
Diagnostic snapshot P0300
- Difficulty
- 6/10 — Intermediate diagnostics
- Est. repair cost
- $120 – $450 (parts + typical shop labor)
- Common symptoms
- Misfire or hesitation under load
- Rough idle
- Check engine light (MIL)
- Reduced power / limp mode
Diagnostic workflow
- Confirm P0300 with a live scan — note pending vs stored and freeze frame data.
- Verify reported symptoms: Misfire or hesitation under load, Rough idle, Check engine light (MIL).
- Inspect wiring/connectors and related sensors before replacing modules.
- Most likely fixes: Spark plug / coil / ignition diagnosis; Cylinder-specific misfire diagnosis (swap / compression / injector); Fuel injector / circuit testing (noid light, resistance, swap).
- Clear codes and road-test; re-scan after two drive cycles if the monitor must set.
Topics
- OBD-II and scan tools (guide)
- Powertrain DTCs (P-prefix) (system)
Related symptoms
- Misfire or hesitation under load (weight 0.900)
- Rough idle (weight 0.880)
- Check engine light (MIL) (weight 0.860)
- Reduced power / limp mode (weight 0.480)
Common fixes (curated)
- Spark plug / coil / ignition diagnosis (rank 1)
- Cylinder-specific misfire diagnosis (swap / compression / injector) (rank 2)
- Fuel injector / circuit testing (noid light, resistance, swap) (rank 3)
Related articles
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- Flashing Check Engine Light Indicates Serious Misfire 2016 Toyota Mirai
- Engine Shakes Violently When Accelerating 2020 Toyota Paseo
- Diagnosing a Check Engine Light with Random Misfire Code 2002 Toyota Prius
- Random Misfire Diagnosis (P0300 Code) 1996 Ford Aerostar
- Random Misfire Diagnosis (P0300 Code) 1997 Toyota Land Cruiser
- Check Engine Light with P0300 Random Misfire Code 2001 Toyota Camry Solara
- Check Engine Light with Random Misfire 1998 Ford F-250
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- What to do when the check engine light is flashing 1999 Ford F-350
- 1997 Ford F-800 Flashing Check Engine Light: What to Do
- Random Misfire Diagnosis (P0300) 1996 Ford La8000
- P0300 field guide: random / multiple cylinder misfire
Diagnostic bundle (JSON)
Machine-readable graph: related codes, symptoms, fixes, topics, articles, and curated sources rows. Append &external=1 for optional YouTube / Google CSE hits when API keys are configured (see web/.env.example).