What Does P0291 Mean?
Cylinder 10 is producing either too much or too little power relative to the other cylinders, and the ECM has confirmed this imbalance is outside acceptable limits. This is the confirmed or secondary stage of the cylinder 10 contribution fault. The driver may experience engine vibration, rough idle, misfires, or reduced power output.
Common Causes
35%
Defective cylinder 10 fuel injector with incorrect spray pattern, stuck open, or partial clog
25%
Mechanical compression loss on cylinder 10 from worn rings, burnt valve, or head gasket breach
20%
High-pressure fuel system issue causing inconsistent fuel delivery to cylinder 10
12%
Electrical fault in cylinder 10 injector driver circuit within ECM or wiring
8%
Camshaft or valve train issue affecting cylinder 10 valve timing or lift
Diagnostic Steps
1
Review Mode 06 cylinder balance test data; identify the exact deviation percentage for cylinder 10 compared to the mean contribution value.
2
Perform an injector flow test using manufacturer-specific diagnostic software to verify cylinder 10 injector delivery volume and timing.
3
Run a cylinder leak-down test on cylinder 10; acceptable leakage is typically less than 10%. Listen for air escaping from intake, exhaust, or crankcase to identify the source.
4
Swap the cylinder 10 injector with a known-good injector from an adjacent cylinder, clear codes, and run the contribution balance test again.
5
If compression and injector tests pass, inspect the valve train for cylinder 10 including cam lobe wear (measure with micrometer against spec) and rocker arm play.
Estimated Repair Cost
$200 - $2,000
Parts + labor, varies by vehicle and location
Cylinder 10 is producing either too much or too little power relative to the other cylinders, and the ECM has confirmed this imbalance is outside acceptable limits. This is the confirmed or secondary stage of the cylinder 10 contribution fault. The driver may experience engine vibration, rough idle,...
The most common cause of P0291 (Cylinder 10 Contribution/Balance Fault) is: Defective cylinder 10 fuel injector with incorrect spray pattern, stuck open, or partial clog
Typical repair costs for P0291 range from $200 to $2,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Driving is possible at reduced speed and load for short distances. A persistent cylinder balance fault can damage the catalytic converter or DPF from unburned fuel and increases mechanical stress on engine internals. Schedule repair soon.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0291 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
