P0284

Universal

Cylinder 8 Contribution/Balance Fault

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

The engine computer has detected that cylinder 8 is not contributing to engine operation in the expected balance with the other cylinders. This can happen when combustion in that cylinder is weaker or otherwise uneven. The code identifies a detected condition, not a confirmed failed part; the cause and exact diagnostic procedure depend on the vehicle's model, year, and engine.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the engine is shaking severely, stalling, losing power, or the check-engine light is flashing, stop driving when it is safe and arrange for diagnosis. Continued operation with a severe misfire can cause further damage. If there is a fuel smell, shut the engine off and seek qualified help.

Common Symptoms

  • The engine may idle roughly or vibrate if cylinder 8 is producing less power than the other cylinders.
  • Acceleration may feel weak or uneven because the engine is not producing balanced power.
  • The engine may misfire, hesitate, or run unevenly, depending on the cause and how strongly cylinder 8 is affected.
  • Fuel economy may worsen if combustion is inefficient.
  • The check-engine light may be on; it may flash if a severe misfire condition is detected.
  • There may be no noticeable symptoms if the imbalance is mild or intermittent.

Common Causes

  • Cylinder 8 may not receive or use fuel normally, potentially due to an injector or fuel-delivery problem.
  • A problem with ignition on cylinder 8, where applicable, may weaken combustion.
  • A damaged, loose, or corroded connector or wiring issue may interfere with a component serving cylinder 8.
  • Low compression, a valve problem, or another mechanical condition may reduce cylinder 8's power contribution.
  • A broader engine or fuel-system condition may contribute to an imbalance; diagnosis is needed to distinguish it from a cylinder-specific fault.

Diagnostic Steps

  1. Check whether the engine is shaking severely, stalling, losing power, or showing a flashing check-engine light. If so, avoid continued driving and arrange diagnosis.
  2. With the engine off and cool, look for obvious damage, loose connections, or corrosion at accessible cylinder 8 wiring and connectors. Do not disconnect components while the engine is running.
  3. If a suitable scan tool is available, record stored codes and freeze-frame information before clearing anything. This can help show when the imbalance was detected.
  4. Note whether the problem occurs at idle, under acceleration, or only intermittently, and share those observations with the technician.
  5. Avoid replacing an injector or other part based only on this code. Cylinder-specific fuel, ignition, wiring, and mechanical checks may be needed.

When to Call a Professional

Compare cylinder contribution or misfire data using a scan tool, then check cylinder 8's ignition, fuel delivery, wiring and connections as applicable. If those checks do not explain the imbalance, test mechanical condition, such as compression or leakdown. Follow service information for the specific vehicle and do not replace an injector or other part based on this code alone.

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Commonly Asked Questions

Does P0284 prove that the cylinder 8 injector has failed?

No. The code describes a cylinder contribution or balance condition. An injector issue is one possibility, but ignition, wiring, mechanical condition, or another engine issue can also cause weak contribution.

Can I keep driving with this code?

That depends on how the engine is running. If it runs smoothly with no loss of power, arrange diagnosis soon. Stop driving when safe if it shakes severely, stalls, loses power, or the check-engine light flashes.

How is the cause usually distinguished?

A technician can compare cylinder contribution or misfire data and then check relevant ignition, fuel-delivery, wiring, and mechanical systems. The appropriate tests depend on the vehicle's engine and service information.

Could there be no symptoms?

Yes. A mild or intermittent imbalance may be detected before the driver notices a change in how the engine runs.

Browse Available Code Guides

Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.