P0672
Cylinder 2 Glow Plug Circuit
Powertrain Ignition System Glow plug control 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The glow plug for cylinder 2 isn't working properly, which helps diesel engines start in cold weather. It's like a heating element that won't turn on when needed.

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Symptoms You May Notice
3 known symptoms for this code
Hard starting, especially in cold weather
White smoke from exhaust on startup
Engine misfiring or rough idle when cold
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the glow plug circuit resistance and heating time during the glow phase before engine cranking. It checks for open circuits, shorts to ground, or excessive resistance that indicates a failed glow plug or wiring fault. If voltage/current is outside normal parameters during the pre-heat cycle, the fault is logged.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Glow plug circuit resistance 0.5–2 ohms per plug >5 ohms or open circuit
Glow plug relay voltage 12–14V during glow phase <8V or no voltage
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Glow plug (cylinder 2)
Remove the glow plug from cylinder 2 and replace with an OEM or equivalent unit; test with a multimeter first to confirm it's open.
2
Glow plug harness connector
Inspect and clean the connector on cylinder 2's glow plug wire; corrosion or loose terminals often cause this code.
3
Glow plug relay or control module
Test the relay with a multimeter; if it won't click or hold voltage, replace it or have the ECU checked for internal faults.