Ford Codes List

Ford-enhanced trouble code lookup
for Ford, Lincoln and Mercury.

Repair Order

655 Ford-enhanced codes on file

Code
P1278

Cylinder 8 High to Low Side Open (7.3L Diesel)

Category
Powertrain - Fuel/Air Metering
Severity
Check Engine Light
Applies to
F-250/F-350 Super Duty with 7.3L Power Stroke
Related
No single generic twin. See OBD Codes List

Findings, check these first

  • Open injector solenoid on cylinder 8
  • Broken harness wire (cylinder 8 runs hot behind the turbo)
  • Unplugged connector
  • Failed injector
  • IDM fault

Standard procedure

  1. Buzz test cylinder 8
  2. Inspect the heat-exposed harness routing
  3. Test injector resistance
  4. Reseat connectors
  5. Replace the injector or repair wiring

Code lookup

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Sources and review

Review: checked against the recorded source material.

  • OBDII.pro: P1278 Ford definition

    live reference page (obdii.pro)

    Supports: Ford-family meaning for P1278: Cylinder #8 High To Low Side Open

    Fetched directly. obdii.pro is a publisher independent of the engine-codes family.

  • P1278 FORD Code: Meaning, Causes, and Symptoms | OBD2 Codes

    live reference page (obd2-codes.co)

    Supports: Ford meaning for P1278: Cylinder #8 High To Low Side Open

    Fetched directly. obd2-codes.co phrasing matches the engine-codes family, so it counts as one publisher.

Last updated 2026-09-05.

Report a correction for P1278. Include your vehicle, the issue and a source if you have one.

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