Engine

P0278 — Cylinder 6 Contribution/Balance Fault

Severity: medium Drive with care, to a shop

What P0278 means

The engine control module compares how evenly the cylinders contribute to engine output, usually by monitoring crankshaft speed. P0278 sets when cylinder 6 produces noticeably less power than the rest. The cause can be fuel delivery, spark, cylinder mechanical condition or wiring.

Symptoms

  • Check engine light on
  • Rough or uneven idle
  • Reduced power and sluggish acceleration
  • Misfire or hesitation under load
  • Higher fuel consumption

Possible causes

  1. Faulty cylinder 6 fuel injector
  2. Worn spark plug or failed ignition coil on cylinder 6
  3. Damaged wiring or poor connector contact at the injector or coil
  4. Low compression in cylinder 6 (rings, valves, head gasket)
  5. Fuel system problems such as low pressure or clogging
  6. ECM fault (rare)

How to diagnose

  1. Scan all codes and freeze frame data, and look for related misfire codes such as P0306
  2. Inspect the wiring and connectors at the cylinder 6 injector and coil
  3. Swap the cylinder 6 coil with a neighbor and see whether the fault follows
  4. Pull and inspect the spark plug, and replace it if worn
  5. Test the injector: resistance, signal and operation
  6. Check fuel pressure
  7. Run a compression or cylinder leak-down test
  8. If everything else checks out, verify ECM power and ground

Common fixes

  • Replace or clean the cylinder 6 injector
  • Replace spark plugs and/or the ignition coil
  • Repair wiring and connectors
  • Perform engine mechanical repair (rings, valves, head)
  • ECM repair or reprogramming as a last resort

Questions and answers

What does P0278 mean?

The ECM detected that cylinder 6 is producing less power than the other cylinders. The injector, spark plug or coil are the usual culprits, with low compression less common.

Can I drive with P0278?

A short, gentle trip to a shop is usually fine. If the check engine light is flashing, stop driving, since overheating the catalytic converter is costly.

How can I quickly find the cause of P0278?

Swap the cylinder 6 coil with a neighboring cylinder's coil and clear the code. If the fault moves to the other cylinder, the coil is bad.

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.