FixItFor.Us
P codepowertrainMedium severity

P0672Cylinder 2 Glow Plug Circuit

A fault has been detected in the cylinder 2 glow plug circuit on a diesel engine, so that plug isn't delivering the commanded heat.

Definition

The glow plug control module energizes each glow plug individually and watches circuit current and voltage for feedback; P0672 stores when the cylinder 2 circuit is open, shorted, or drawing abnormal current. A single failed plug shows up almost entirely in cold weather: longer cranking, a rough idle or miss on cylinder 2 until combustion chamber temperatures rise, and white smoke at startup. The MIL or wait-to-start lamp illuminates and the vehicle can fail an emissions inspection; on common-rail diesels that pulse glow plugs after start or during regeneration, combustion quality and DPF performance can also be affected.

Common causes

  • Open (burned-out) cylinder 2 glow plug element
  • Corroded or loose connection at the cylinder 2 plug terminal
  • Broken or chafed wiring between the control module and the plug
  • Carbon-fouled plug tip changing circuit resistance
  • Failed glow plug control module driver for that channel

Common misdiagnoses

  • Replacing the glow plug control module before testing the plug itself
  • Replacing the battery for hard cold starting
  • Replacing the cylinder 2 injector for a cold-only miss
  • Treating cold-start white smoke as a head gasket problem

Troubleshooting steps

  1. 1.Test cylinder 2 glow plug resistance

    Disconnect the lead and measure terminal-to-ground; roughly 0.5-2 ohms is typical and OL means the element is open.

  2. 2.Benchmark against the other cylinders

    Identical plugs on the same engine should read within a few tenths of an ohm of each other; an outlier is the failure.

  3. 3.Inspect the connection and harness

    Check the terminal nut torque, look for oil or coolant wicking into the connector, and trace the lead for heat damage near the exhaust side.

  4. 4.Confirm commanded voltage during a glow cycle

    Back-probe the cylinder 2 lead during pre-glow and verify the module delivers the specified voltage profile (many modern systems use PWM-controlled 5-11 V rather than steady battery voltage).

  5. 5.Replace the module only after the circuit proves good

    A good plug plus verified wiring with no output during commanded pre-glow condemns the glow plug control module channel.

Related codes