Fuel and air

P0263 — Cylinder 1 Contribution/Balance Fault

Severity: medium Drive with care, to a shop

What P0263 means

The engine control module compares how evenly the cylinders work, usually by tracking tiny changes in crankshaft speed. P0263 means cylinder 1 is contributing less power than the rest and the ECM cannot correct it by adjusting fuel. The usual culprit is the injector or its circuit, with mechanical problems in the cylinder less common.

Symptoms

  • Check Engine light on
  • Rough or uneven idle
  • Loss of power and sluggish acceleration
  • Higher fuel consumption
  • Misfire or stumble tied to cylinder 1
  • White smoke from the exhaust (diesel)

Possible causes

  1. Faulty, clogged or weak cylinder 1 fuel injector
  2. Damaged wiring or a corroded or loose connector in the injector circuit
  3. Low compression in cylinder 1 (rings, valve, head gasket)
  4. Low fuel pressure from a weak pump or clogged filter
  5. Incorrect injector coding or adaptation (diesel)
  6. ECM fault or bad sensor data (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data, and look for related misfire codes such as P0301
  2. Inspect the cylinder 1 injector connector and harness for damage and corrosion
  3. Test injector resistance and the control signal with a multimeter or scope
  4. Swap the cylinder 1 injector with a neighbor and see if the fault follows it
  5. Measure fuel pressure and check the filter and pump
  6. Check the spark plug and ignition coil on cylinder 1 (gasoline engines)
  7. Run a compression or leak-down test on cylinder 1
  8. On diesels, review per-cylinder correction values and injector coding

Common fixes

  • Clean or replace the cylinder 1 injector
  • Repair the injector wiring or connector
  • Replace the fuel filter or pump if pressure is low
  • Fix the cause of low compression: valves, rings or head gasket
  • Recode injectors or update ECM software; replace the ECM only as a last resort

Questions and answers

What does P0263 mean?

It means cylinder 1 is contributing less to engine output than the other cylinders. The most common causes are the injector, its wiring or low compression.

Can I drive with P0263?

Only in a limited way and to a repair shop. If the engine runs rough or the check engine light flashes, stop to avoid damaging the catalytic converter.

How can I tell if the injector is the problem?

Swap the cylinder 1 injector with a neighboring one. If the fault moves to the other cylinder, the injector is bad; if not, look at wiring or engine mechanics.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.