What Does P0278 Mean?
The ECM has detected a cylinder 6 contribution or balance fault, indicating cylinder 6 is not producing its expected torque contribution. Crankshaft speed analysis shows cylinder 6's power stroke is weaker than the other cylinders. Found on 6+ cylinder engines. The driver will notice rough idle, vibration, reduced power, and a general misfire-like sensation.
Common Causes
35%
Cylinder 6 fuel injector with degraded flow, restricted nozzle, or weak spray pattern
25%
Low compression on cylinder 6 from mechanical wear — rings, valves, or head gasket
20%
Injector wiring or ECM driver fault reducing fuel pulse to cylinder 6
12%
Intake restriction or vacuum leak at cylinder 6 intake port
8%
Glow plug failure (diesel) or ignition failure (gasoline) on cylinder 6
Diagnostic Steps
1
Review cylinder contribution rates in live data — compare cylinder 6 against all others to confirm it is the weak cylinder and determine the severity of the imbalance.
2
Perform a compression test on all cylinders — cylinder 6 should be within 10% of the highest. If low, perform a leak-down test to determine if the leak is past the rings, intake valve, exhaust valve, or head gasket.
3
Test the cylinder 6 injector by performing a leak-back test (diesel) or flow bench comparison — excessive return flow indicates internal wear that prevents proper fuel delivery.
4
Monitor injection quantity correction values for cylinder 6 — large positive corrections indicate the ECM is already compensating for a weak injector, confirming the root cause.
5
Swap the cylinder 6 injector with a known-good cylinder, clear codes, and test-drive — this is the definitive test to confirm injector-related contribution faults.
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
The ECM has detected a cylinder 6 contribution or balance fault, indicating cylinder 6 is not producing its expected torque contribution. Crankshaft speed analysis shows cylinder 6's power stroke is weaker than the other cylinders. Found on 6+ cylinder engines. The driver will notice rough idle, vib...
The most common cause of P0278 (Cylinder 6 Contribution/Balance Fault) is: Cylinder 6 fuel injector with degraded flow, restricted nozzle, or weak spray pattern
Typical repair costs for P0278 range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Driveable with reduced power, but prolonged operation with cylinder imbalance causes elevated exhaust temperatures and risks catalytic converter or turbo damage. Schedule repair within a few days.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0278 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection / Engine Mechanical
Difficulty
Type
Generic (SAE)
Recommended Tools
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