What are the common causes of P0263?

A weak or clogged cylinder 1 fuel injector. Low compression in cylinder 1. A worn or fouled spark plug or coil on cylinder 1. A vacuum leak at the cylinder 1 intake runner. Low fuel pressure affecting all cylinders.

Run an injector balance test and compare cylinder 1 to the others. Do a compression and leak down test on cylinder 1. Inspect the cylinder 1 plug and coil for wear. Check fuel pressure at the rail. Replace injector 1 if it is weak or clogged. Clear the code and retest.

P0263

Cylinder 1 Contribution/Balance

System: Injector circuits (P code)
Lamp: Check Engine Light
Category: Powertrain - Fuel/Air Metering

What it means

P0263 means Cylinder 1 Contribution/Balance.

Check these first

A weak or clogged cylinder 1 fuel injector
Low compression in cylinder 1
A worn or fouled spark plug or coil on cylinder 1
A vacuum leak at the cylinder 1 intake runner
Low fuel pressure affecting all cylinders

What to do next

Run an injector balance test and compare cylinder 1 to the others
Do a compression and leak down test on cylinder 1
Inspect the cylinder 1 plug and coil for wear
Check fuel pressure at the rail
Replace injector 1 if it is weak or clogged
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.