What Does P0263 Mean?
The ECM has detected a contribution or balance fault on cylinder 1, meaning this cylinder is not producing its expected share of engine power. The ECM monitors crankshaft acceleration per cylinder firing event, and cylinder 1 is deviating significantly from the others. This indicates a mechanical or fuel delivery problem specific to cylinder 1.
Common Causes
30%
Faulty cylinder 1 fuel injector delivering incorrect fuel quantity
30%
Low compression on cylinder 1 due to worn piston rings, leaking valve, or blown head gasket
25%
Cylinder 1 glow plug failure (diesel) or ignition component failure (gas) causing poor combustion
15%
Intake manifold leak or restricted intake runner for cylinder 1
Diagnostic Steps
1
Step 1: Perform a relative compression test using cranking RPM analysis — compare cylinder 1 to the others. Deviation greater than 10% indicates a mechanical issue.
2
Step 2: If compression is suspect, perform a traditional compression test on cylinder 1 — minimum spec is typically 120 PSI for gasoline or 300 PSI for diesel.
3
Step 3: Monitor cylinder 1 fuel injector balance rates or contribution values on the scan tool — large deviations indicate an injector delivering too much or too little fuel.
4
Step 4: For diesel engines, test the cylinder 1 glow plug resistance (typically 0.5-2 ohms). For gas engines, inspect spark plug and coil.
5
Step 5: If compression and fuel delivery are normal, check for intake air leaks at the cylinder 1 intake port using a smoke machine.
Estimated Repair Cost
$150 - $2,000
Parts + labor, varies by vehicle and location
The ECM has detected a contribution or balance fault on cylinder 1, meaning this cylinder is not producing its expected share of engine power. The ECM monitors crankshaft acceleration per cylinder firing event, and cylinder 1 is deviating significantly from the others. This indicates a mechanical or...
The most common cause of P0263 (Cylinder 1 Contribution/Balance Fault) is: Faulty cylinder 1 fuel injector delivering incorrect fuel quantity
Typical repair costs for P0263 range from $150 to $2,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle will run rough with reduced power. Drivable but the root cause may worsen if ignored. Schedule diagnosis and repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0263 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
Engine Mechanical / 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.
