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P codepowertrainMedium severity

P0675Cylinder 5 Glow Plug Circuit

A fault has been detected in the cylinder 5 glow plug circuit on a diesel engine, so that plug can't heat its cylinder for cold starts.

Definition

On diesels with five or more cylinders, the glow plug control module drives each plug on its own circuit and monitors feedback current; P0675 stores when the cylinder 5 circuit shows an open, a short, or abnormal current draw. Expect the classic single-plug pattern: harder starting as temperatures drop, a cold miss on cylinder 5 with white smoke, and normal behavior once warm. The MIL or glow plug indicator illuminates and the code fails an emissions inspection while current; multiple simultaneous cylinder codes usually point to a shared supply, ground, or module fault rather than several plugs failing at once.

Common causes

  • Open cylinder 5 glow plug element
  • Corroded, loose, or oil-soaked terminal at the plug
  • Wiring damage between the glow plug control module and cylinder 5
  • Carbon-insulated plug tip altering circuit resistance
  • Faulty glow plug control module output

Common misdiagnoses

  • Replacing the glow plug control module for a single open plug
  • Replacing the batteries or starter for slow cold starting
  • Replacing the cylinder 5 injector for a cold-only miss
  • Chasing low compression for what is a heating-circuit fault

Troubleshooting steps

  1. 1.Measure cylinder 5 glow plug resistance

    Disconnect the lead and read terminal-to-ground; approximately 0.5-2 ohms is normal for most modern plugs and OL means open.

  2. 2.Survey the whole plug set

    Reading every plug identifies the failed unit and flags aging siblings — plugs tend to fail in sequence on high-mileage engines.

  3. 3.Inspect the cylinder 5 feed and terminal

    Check terminal torque, look for corrosion or oil intrusion, and trace the harness for chafe or heat damage, especially on rear cylinders where access hides problems.

  4. 4.Verify commanded voltage at the plug

    During a scan-tool-commanded or cold-start glow cycle, confirm the specified voltage reaches the cylinder 5 terminal.

  5. 5.Replace the plug or repair the circuit and retest

    Torque the new plug to spec (typically 8-15 Nm), clear the code, and confirm normal current on repeat glow cycles.

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