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Articles · Jaguar · I-Pace · 2026 · P0300

P0300

P0300 field guide: random / multiple cylinder misfire

By ClearTheCode · Published 2026-05-18 · ~3 min read

How to narrow P0300 quickly: pattern recognition, fuel vs ignition vs mechanical causes, and when to stop replacing parts.

At a glance 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

  1. Confirm P0300 with a live scan — note pending vs stored and freeze frame data.
  2. Verify reported symptoms: Misfire or hesitation under load, Rough idle, Check engine light (MIL).
  3. Inspect wiring/connectors and related sensors before replacing modules.
  4. Most likely fixes: Spark plug / coil / ignition diagnosis; Cylinder-specific misfire diagnosis (swap / compression / injector); Fuel injector / circuit testing (noid light, resistance, swap).
  5. Clear codes and road-test; re-scan after two drive cycles if the monitor must set.

At a glance: difficulty, repair cost, and diagnostic workflow

  • Difficulty Rating: 6/10 — 6/10 — Intermediate diagnostics
  • Common Symptoms: Misfire or hesitation under load; Rough idle; Check engine light (MIL); Reduced power / limp mode
  • Estimated Repair Cost: $120–$450 (parts + typical shop labor)
  • OEM Tooling Required: Standard OBD-II scanner and hand tools

Diagnostic workflow:

  1. Confirm P0300 with a live scan — note pending vs stored and freeze frame data.
  2. Verify reported symptoms: Misfire or hesitation under load, Rough idle, Check engine light (MIL).
  3. Inspect wiring/connectors and related sensors before replacing modules.
  4. Most likely fixes: Spark plug / coil / ignition diagnosis; Cylinder-specific misfire diagnosis (swap / compression / injector); Fuel injector / circuit testing (noid light, resistance, swap).
  5. Clear codes and road-test; re-scan after two drive cycles if the monitor must set.

See the P0300 code reference and topic hub for related guides.

What P0300 is not

P0300 means multiple cylinders are misfiring or the PCM cannot isolate a single cylinder. It is not automatically “bad coil packs” — context from freeze frame, RPM/load, and fuel trim matters.

A sane sequence

  1. Verify crankshaft / camshaft correlation and timing when recent service or noise suggests it.
  2. Read cylinder-specific misfire counts if the PCM exposes them; trend counts vs RPM.
  3. Ignition primary/secondary tests where accessible; swap coil-on-plug only as a structured experiment with before/after counts.
  4. Injector balance or fuel trim per bank when misfire follows lean or rich behavior.
  5. Mechanical health — relative compression or in-cylinder waveform when ignition and fuel look stable.

Safety

Raw fuel dilution, catalyst overheating, and NVH can escalate quickly. Address chronic misfire before repeated wide-open-throttle tests.

CarCOX diagnostic notes — not a substitute for OEM service procedures or licensed repair data.

Frequently asked questions

How urgent is this problem?

If symptoms are worsening or safety systems are affected, diagnose soon; minor issues can often wait for a scheduled service visit.

Can I drive with this issue?

Short trips may be acceptable for some faults, but stop driving if you notice overheating, loss of braking, steering problems, or strong fuel smells.

Do I need a dealer scan tool?

A basic OBD-II scanner helps confirm codes; some steps still need visual checks and meter tests described above.

Helpful links

On ClearTheCode

Cited catalog sources

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