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DTC code page

P0307: Cylinder 7 Misfire Detected

Quick answer: The ECU detected misfire activity concentrated on cylinder 7.

Drivers also search this fault as cylinder 7 misfire, misfire cylinder 7, number 7 cylinder misfire.

Severity: high Family: powertrain Related paths: 10
Meaning

What P0307 usually means

P0307 is the cylinder-7 branch of the single-cylinder misfire family. It matters most on engines where cylinders 7 and 8 live on the same rear bank, because heat, wiring tension, plug-well contamination, and maintenance access can all distort the usual coil-versus-injector diagnosis if you rush it.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Inspect the cylinder 7 area carefully for heat damage, oil intrusion, or brittle connectors before ordering parts.
  • Check whether the vehicle recently had plug or coil service, because rear-bank installation mistakes are common.
  • If catalyst or rich-running codes are also present, keep converter risk in mind while the misfire remains active.
Driving risk

Can you keep driving?

P0307 should be treated as high urgency when active. If the engine shakes, backfires, or flashes the MIL, continued driving risks converter damage and poor drivability.

High urgency: If symptoms are active, reduce driving and diagnose quickly before secondary damage builds.
Likely causes

Common causes behind this code

  • Cylinder 7 plug or coil failure
  • Boot arcing or contamination in the plug well
  • Injector flow or electrical control problem on cylinder 7
  • Low compression or valvetrain sealing problem
  • Harness damage or connector stress near the rear bank

Cause phrases often tied to this code: ignition coil, spark plug, injector, compression loss, rear bank heat.

Diagnostic order

Suggested workflow

  1. Inspect cylinder 7 ignition components and the surrounding harness routing.
  2. Swap the plug or coil with another cylinder when practical to see whether the fault follows.
  3. Confirm injector command and listen or scope the injector rather than assuming it is fine.
  4. Run compression testing if ignition and fuel checks do not resolve the diagnosis.
  5. After repair, confirm the engine stays smooth during idle, cruise, and moderate load.
Avoid guesswork

Common mistakes

  • Replacing only the coil when oil-contaminated plug wells are the real repeat failure source.
  • Ignoring the difference between a stored history code and an active flashing-MIL misfire.
  • Treating cylinder 7 and 8 as interchangeable without confirming engine-specific cylinder numbering.
Repair path

Practical fix guidance

  • Fix the proven cylinder 7 fault and any contamination or wiring issue that helped create it.
  • If the misfire persisted long enough to trigger catalyst efficiency faults later, inspect that downstream damage separately.
  • Use the same temperature and load conditions from freeze-frame data to validate the repair.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0307

Useful when the driver knows the wording but not the exact DTC yet.

  • cylinder 7 misfire
  • misfire cylinder 7
  • number 7 cylinder misfire
Related search intent

Queries this page can answer naturally

  • P0307 code meaning
  • what does P0307 mean
  • cylinder 7 not firing
  • P0307 flashing check engine light
FAQ

Quick questions about P0307

Is P0307 mostly a truck or V8 code?

It appears most often where cylinder 7 exists, so V8 and some larger engines see it more naturally than four-cylinder layouts.

Can oil in the plug well cause P0307?

Yes. Oil contamination can damage the boot, promote arcing, and keep the misfire coming back.

What if P0307 and P0308 appear together?

That often points you toward a shared rear-bank issue such as wiring, contamination, or fuel and mechanical problems affecting that side.