GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra - 4WD 🢒 DTC 🢒 DTC P268C-P268F or P2690-P2693

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P268C: Injector 1 Calibration Incorrect

DTC P268D: Injector 2 Calibration Incorrect

DTC P268E: Injector 3 Calibration Incorrect

DTC P268F: Injector 4 Calibration Incorrect

DTC P2690: Injector 5 Calibration Incorrect

DTC P2691: Injector 6 Calibration Incorrect

DTC P2692: Injector 7 Calibration Incorrect

DTC P2693: Injector 8 Calibration Incorrect

Circuit/System Description

The control functions for the fuel injection system are integrated in the engine control module (ECM). During the manufacturing process, each injector's flow rate is measured and recorded as injection quantity adjustment (IQA) flow rate data. The flow rate data is then etched as a hexadecimal number on the body of the injector. This data, together with the injector's cylinder position, is stored in the memory of both the glow plug control module (GPCM) and the ECM. When the ignition is turned ON, the GPCM and the ECM compare the IQA Data . If any of the injector flow rate numbers are incorrect in either of the control modules, this diagnostic will set the appropriate DTC.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The fuel injector calibration flow rate data is incorrect .

Action Taken When the DTC Sets

DTCs P268C, P268D, P268E, P268F, P2690, P2691, P2692 and P2693 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P268C, P268D, P268E, P268F, P2690, P2691, P2692 and P2693 are Type A DTCs.

Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Output Controls
    •  Scan Tool Data Definitions

Circuit/System Verification
  1. Review the Display ECM & GPCM Inj. Flow Rates function with a scan tool. All cylinders should be programmed with a flow rate number. Both the GPCM and the ECM should be programmed with the same flow rate numbers for the corresponding cylinders.
    2. ⇒If flow rate numbers are incorrect, refer to Fuel Injector Flow Rate Programming .
  2. Engine running, observe the DTC information with a scan tool. DTCs P268C, P268D, P268E, P268F, P2690, P2691 or P2693 should not set.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.