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P codepowertrainMedium severity

P0676Cylinder 6 Glow Plug Circuit

A fault has been detected in the cylinder 6 glow plug circuit on a diesel engine, preventing proper cold-start heating in that cylinder.

Definition

The glow plug control module powers the cylinder 6 glow plug on a dedicated circuit and verifies its current draw during pre-glow, post-glow, and any regeneration-support phases; P0676 sets when that circuit is open, shorted, or out of range. A single inoperative plug causes extended cranking in cold weather, a cold miss and shake attributable to cylinder 6, and white smoke that clears with warm-up, while hot restarts remain normal. The MIL or wait-to-start lamp comes on and the vehicle fails an OBD emissions check while the code is current. If several cylinder glow codes set together, suspect a common feed, ground, or the control module itself before condemning multiple plugs.

Common causes

  • Burned-out (open) cylinder 6 glow plug
  • Corroded or loose terminal connection at the plug
  • Broken or chafed wiring from the control module to cylinder 6
  • Carbon deposits on the plug tip
  • Failed glow plug control module driver channel

Common misdiagnoses

  • Replacing the glow plug control module when the plug is simply open
  • Replacing batteries for cold-start complaints
  • Replacing the cylinder 6 injector for a cold miss
  • Replacing a glow plug relay on individually controlled systems that have none

Troubleshooting steps

  1. 1.Resistance-test the cylinder 6 glow plug

    With the lead disconnected, terminal-to-ground should measure roughly 0.5-2 ohms depending on plug design; OL confirms an open element.

  2. 2.Compare against the other five plugs

    Consistent readings across the set with one outlier pinpoints the failure and rules out systemic causes.

  3. 3.Inspect the connection and harness routing

    Cylinder 6 is often the hardest to access — check the terminal nut, connector condition, and harness chafe points carefully before condemning parts.

  4. 4.Verify module output during a glow cycle

    Back-probe or use a test light rated for the circuit during commanded pre-glow to confirm the specified voltage arrives at the plug.

  5. 5.Repair, clear, and confirm

    After replacing the plug (torqued to spec, typically 8-15 Nm) or repairing wiring, clear the code and verify it stays clear through multiple cold-start glow cycles.

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