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DTC codes / P02xx · Fuel and air metering (injector circuits) / P0278

P0278Cylinder 6 Contribution/Balance

P0278 is a generic powertrain code indicating that the engine control module (ECM) has detected a problem with cylinder 6's contribution to engine power, meaning that cylinder is not producing its fair share of torque compared to the others. The ECM typically monitors crankshaft speed fluctuations and compares each cylinder's power stroke to identify a weak or misfiring cylinder.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Rough idle or shaking, especially noticeable when the engine is cold or under load
  • Noticeable loss of power and reduced fuel economy
  • Engine misfire that may feel like a stumble or hesitation during acceleration
  • Check engine light illuminated, sometimes flashing if the misfire is severe
  • Often no symptoms besides the warning light, particularly if the imbalance is minor
  • Possible vibration or shuddering during highway cruising

Common causes, most likely first

  1. Faulty ignition coil or spark plug on cylinder 6
  2. Clogged or leaking fuel injector on cylinder 6
  3. Low compression due to worn piston rings, valves, or head gasket issues
  4. Vacuum leak affecting the intake runner for cylinder 6
  5. Wiring or connector problem to the cylinder 6 injector or coil
  6. Mechanical valvetrain issue such as a worn cam lobe or lifter
  7. Engine control module (ECM) software or internal fault (rare)

How to diagnose and fix it

  1. Perform a visual inspection of the cylinder 6 ignition coil, spark plug, and injector connectors for damage or corrosion
  2. Swap the ignition coil and spark plug from cylinder 6 with a known-good cylinder to see if the misfire moves
  3. Use a scan tool to check for pending or stored misfire codes and view live misfire counters per cylinder
  4. Run a compression test and a cylinder leak-down test on cylinder 6 to rule out mechanical problems
  5. Test the fuel injector for cylinder 6 with a noid light or injector balance test
  6. Check for vacuum leaks at the intake manifold and around the cylinder 6 runner
  7. If all else fails, inspect the ECM and wiring harness for faults, and consider reprogramming or replacement

Cylinder 6 Contribution Code Traps

  • A P0278 can be set by a problem that is not cylinder-specific, such as a vacuum leak that affects the entire bank or a faulty mass airflow sensor (MAF) that skews fuel trims.
  • Many technicians replace the ignition coil and spark plug on cylinder 6 only to find the misfire persists because the root cause is a clogged injector or low compression.
  • The code may appear intermittently and not trigger a flashing check engine light, leading some to ignore it, but prolonged driving with a misfire can damage the catalytic converter.
  • On engines with active fuel management or cylinder deactivation, a P0278 can be set by a faulty lifter or solenoid that prevents cylinder 6 from contributing power when it should.
  • Always check for technical service bulletins (TSBs) for the specific vehicle, as some manufacturers have known issues with injector or coil failures on certain cylinders.

Can I keep driving with P0278?

It is generally safe to drive with a P0278 code if the check engine light is steady and the engine runs smoothly, but avoid heavy acceleration or towing. If the light flashes or the engine runs rough, stop driving and seek repair immediately to prevent catalytic converter damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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