Engine

P0284 — Cylinder 8 Contribution/Balance Fault

Severity: medium Drive with care, to a shop

What P0284 means

P0284 means the engine computer, usually by watching crankshaft speed changes, detected that cylinder 8 is contributing less than the others or is out of balance. Normally every cylinder gets the same fuel, spark and compression, so each produces about equal power. A fault in any of these on cylinder 8 can set the code.

Symptoms

  • Check engine light on or flashing
  • Rough or uneven idle
  • Loss of power and sluggish acceleration
  • Worse fuel economy
  • Engine shake or vibration under load
  • Hesitation or stumbling when accelerating

Possible causes

  1. Faulty or clogged cylinder 8 fuel injector
  2. Failed ignition coil or worn spark plug on cylinder 8
  3. Damaged, corroded or loose injector or coil wiring and connectors
  4. Low compression in cylinder 8 (rings, valves, head gasket)
  5. Vacuum leak near cylinder 8
  6. Rarely, a PCM fault or failed driver circuit

How to diagnose

  1. Scan for all codes and freeze frame data, and note any misfire codes.
  2. Inspect the cylinder 8 injector and coil connectors and harness for damage or corrosion.
  3. Swap the cylinder 8 coil with another cylinder and see whether the fault follows it.
  4. Inspect the cylinder 8 spark plug and replace it if worn or fouled.
  5. Test injector resistance and check that it clicks or pulses with a stethoscope or scope.
  6. Check for vacuum leaks at hoses and intake manifold gaskets.
  7. Run a compression or cylinder leak-down test on cylinder 8.
  8. If everything checks out, test PCM power, grounds and driver signals.

Common fixes

  • Clean or replace the cylinder 8 fuel injector
  • Replace the spark plug and/or ignition coil
  • Repair damaged wiring and connectors
  • Fix any vacuum leaks
  • Repair internal engine problems causing low compression
  • PCM repair or reprogramming (last resort)

Questions and answers

What does P0284 mean?

The engine computer found that cylinder 8 is producing less power than, or is unbalanced with, the other cylinders. Check spark, fuel delivery and compression on that cylinder.

Can I drive with P0284?

Only for a short distance and with light loads. If the check engine light is flashing, stop to avoid damaging the catalytic converter.

How do I find the cause of P0284 quickly?

Swap the cylinder 8 coil with another cylinder and see whether the code moves. If it does not, check the injector, wiring and compression.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.