P0672 - Cylinder 2 Glow Plug Circuit/Open
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Cylinder 2 Glow Plug Circuit/Open (P0672). The module sees no circuit at all — broken wire, backed-out pin, or a failed sensor. The fault is isolated to cylinder 2, positioned on the inner block section with asymmetric intake runner pulses. This directly impacts individual cylinder volumetric efficiency, firing synchronization, and dedicated harness branch loading.
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Cylinder 2 Glow Plug Circuit/Open – Permanent B+ Supply | Voltage (V) | 12.4 - 12.7 V (ignition OFF) / 13.5 - 14.7 V (engine running) | At module supply pins |
| Cylinder 2 Glow Plug Circuit/Open – Ignition-Switched Supply | Voltage (V) | 11.8 - 14.4 V | Ignition ON |
| Cylinder 2 Glow Plug Circuit/Open – Ground Connections Voltage Drop | Voltage (V) | < 0.1 V per ground point | Under load to battery negative |
| Cylinder 2 Glow Plug Circuit/Open – 5 V Reference Outputs | Voltage (V) | 4.95 - 5.05 V per circuit | Ignition ON, sensors unplugged one at a time |
At module supply pins
Ignition ON
Under load to battery negative
Ignition ON, sensors unplugged one at a time
Oscilloscope Waveform Analysis
500 ms/div, 5 V/divPossible Causes
Open circuit, damaged wiring harness, or disconnected plug at Cylinder 2 Glow Plug Circuit/Open
Mid-block harness fatigue (cylinder 2): Wiring friction against valve cover bracket and hydraulic standing pressure waves in fuel rail between cylinder 1 and 2.
Asymmetric intake tumble:Tumble airflow disruption and localized carbon deposits on intake valves of cylinder 2.
Chafed or pinched wiring harness along the signal path to Cylinder 2 Glow Plug Circuit/Open
Poor ground connection or excessive voltage drop (> 0.1 V) at the ground point for Cylinder 2 Glow Plug Circuit/Open
Defective internal output driver or reference circuit in the control module for Cylinder 2 Glow Plug Circuit/Open
Symptoms
5
Recommended Solution
Swap component on cylinder 2 over to cylinder 3 and clear DTCs to confirm if fault follows.
Smoke test intake manifold runner gasket at cylinder 2 to rule out unmetered false air and pressure standing waves.
Verify continuity (< 0.5 Ω) on the signal wire between the component plug and the ECM header connector.
Verify loaded supply voltage and harness terminal pins at Cylinder 2 Glow Plug Circuit/Open.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Cylinder 2 Glow Plug Circuit/Open.
Inspect module enclosure and connector headers for water ingress, fretting corrosion, or PCB thermal damage.
Mechanic's Tip
Pro-tip for cylinder 2: Intake manifold runner geometry exposes cylinders 2 and 3 to distinct pressure pulsation waves. Smoke test the intake runner seals thoroughly.