P268F: Cylinder 4 Injector Data Incompatible

P268F flags missing or unusable correction data for the injector in cylinder 4. On four-cylinder diesels it closes the series: GM's 2014 table 14OBDG04 and 2016 table 16OBDG04 list P268C to P268F and nothing beyond. The 2014 version checks the IQA checksum before each trip and rates the fault Type B, so the lamp waits for a second failed trip; the 2016 version uses the DID $63 write check and Type A. Six- and eight-cylinder engines from GM and Ford use the code as well. CARB requires that a wrong compensation be detected and, where feasible, traced to the specific injector. A single unmatched injector seldom causes clear symptoms, but emissions and noise can rise.

Cylinder 4 is numbered according to the manufacturer: check your engine's manual before working on it.

Symptoms

• Check engine light on
• Possible rough idle or higher combustion noise

Most likely causes

• New cylinder 4 injector fitted without code programming
• Code typed incorrectly into the scan tool
• Used or replacement controller carrying another engine's codes

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and wiring of the injector indicated
2. Measure the resistance and compare it with the manufacturer's specification
3. Check the control signal with an oscilloscope; on direct injection or diesel engines, leave this to a repair shop because of the high voltages
4. On diesels, check the per-cylinder injection corrections

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P268F means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 6: Control modules and outputs
• 8F: Specific fault in that system

Frequently asked questions

Can I keep driving with code P268F?

Drive as little as possible and go to a repair shop. If you smell fuel or the engine is shaking badly, do not keep driving.

What causes code P268F?

The most common causes are: new cylinder 4 injector fitted without code programming; code typed incorrectly into the scan tool; used or replacement controller carrying another engine's codes.

Related codes

• P268ECylinder 3 Injector Data Incompatible
• P2690Cylinder 5 Injector Data Incompatible
• P2696Injector Data Incompatible
• P0204Cylinder 4 Injector A Circuit/Open
• P02F1Cylinder 4 Injector Circuit Range/Performance

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 14OBDG04 Engine Diagnostics
• gsi.ext.gm.com: 16OBDG04 Engine Diagnostics
• fordservicecontent.com: obd summary diesel 2023

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.