What Does P0279 Mean?
This code indicates a cylinder 6 contribution or balance fault where cylinder 6 is producing less power than the other cylinders, detected through crankshaft speed variation analysis. In some ECM calibrations, P0279 represents the low-side balance fault for cylinder 6. The driver will experience rough running, vibration, reduced power, and possible increased exhaust emissions.
Common Causes
35%
Cylinder 6 fuel injector failing — restricted flow, worn nozzle, or poor atomization
25%
Compression loss on cylinder 6 — worn rings, valve recession, or gasket failure
20%
Electrical issue in the cylinder 6 injector circuit reducing fuel delivery
12%
Air distribution imbalance starving cylinder 6 of intake charge
8%
Exhaust backpressure or EGR flow imbalance affecting cylinder 6
Diagnostic Steps
1
Confirm the cylinder 6 imbalance by reviewing live data contribution rates — check if the deviation is consistent across different engine speeds and loads.
2
Perform a relative compression test using cranking RPM analysis to quickly identify if cylinder 6 has a mechanical disadvantage compared to the other cylinders.
3
Swap the cylinder 6 injector with a known-good cylinder, clear codes, and test — this isolates whether the fault is injector-related or position-related.
4
If the fault stays at cylinder 6 after injector swap, perform a full leak-down test at TDC — listen for air escaping at the intake, exhaust, oil fill cap, and cooling system to identify the leak path.
5
On turbodiesel engines, check for boost pressure distribution issues by inspecting the intake manifold runners for carbon buildup or damage that could restrict airflow to cylinder 6 specifically.
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
This code indicates a cylinder 6 contribution or balance fault where cylinder 6 is producing less power than the other cylinders, detected through crankshaft speed variation analysis. In some ECM calibrations, P0279 represents the low-side balance fault for cylinder 6. The driver will experience rou...
The most common cause of P0279 (Cylinder 6 Contribution/Balance Fault) is: Cylinder 6 fuel injector failing — restricted flow, worn nozzle, or poor atomization
Typical repair costs for P0279 range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle can be operated at light loads for short distances. Continued operation with a cylinder contribution fault risks overheating the exhaust aftertreatment system and may trigger limp mode. Have it repaired soon.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0279 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection / Engine Mechanical
Difficulty
Type
Generic (SAE)
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