How to Read the Check-Engine Codes on a Ford F-350 6-Liter Diesel Truck

by Allen Moore
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The Ford Motor Company’s 6.0-liter-diesel-equipped F-350 has a drivetrain controlled by three computers: the powertrain control module, the transmission control module and the fuel-injection control module. When the Check Engine light turns on, one or more of these three modules has detected an error in their monitored systems and generated a diagnostic trouble code to correspond to that error. The first step in troubleshooting the problem is reading the codes.

Step 1

Locate the diagnostic connection port under the driver side dashboard. The port is roughly ½-inch tall by 2 inches wide. Remove the protective cap from the port and plug the scan tool diagnostic connector into the port. The port resembles a multi-pin printer port for a computer system.

Step 2

Follow the specific procedure in you scan tool operator’s manual for running a self test on the powertrain control module, the transmission control module and the fuel-injector control module. At each stage of the test when the codes display for each module, write the codes on your notepad, under the proper module designation. These codes correspond to specific pinpoint tests required in order to complete a full diagnosis of the problem.

Step 3

Complete the self test as specified in your scan tool operator’s manual. Select “No” when prompted to delete the codes. These codes should remain in the module’s memory. Once the problem's diagnosis and repair is complete, rerun the test and delete the codes.

Step 4

Disconnect the scan tool's connector from the port under the dashboard when prompted to do so by your scan tool. Reinstall the protective cap on the diagnostic connection port.

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