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DTC code page

P0673: Cylinder 3 Glow Plug Circuit/Open

Quick answer: The ECU detected an open or fault in the cylinder 3 glow plug circuit.

Drivers also search this fault as cylinder 3 glow plug circuit, glow plug 3 open, cylinder 3 preheat fault.

Severity: medium Family: powertrain Related paths: 10
Meaning

What P0673 usually means

P0673 flags a problem in the cylinder 3 preheat path. The code matters because diesel cold-start quality is cumulative: one weak cylinder might be manageable, but one weak cylinder combined with marginal battery speed, aging compression, or another tired plug can turn into a very noticeable hard-start complaint. P0673 therefore should be treated as part of a cold-start system diagnosis, not as an isolated electrical trivia code.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Verify cylinder numbering before targeting parts on V-engines or less familiar layouts.
  • Check plug resistance and compare with the rest of the set for context.
  • Inspect for connector corrosion or heat damage at the cylinder 3 plug.
Driving risk

Can you keep driving?

P0673 is usually manageable once the engine is running, but it should not be left alone if cold starts are becoming inconsistent or smoky.

Moderate urgency: This code often allows short-term driving, but the right fix usually comes faster when you diagnose it early instead of waiting for more codes.
Likely causes

Common causes behind this code

  • Open cylinder 3 glow plug
  • Damaged or corroded feed wire to cylinder 3
  • Loose connector or poor terminal grip
  • High resistance in the glow plug harness
  • Failed controller channel on cylinder 3 output

Cause phrases often tied to this code: bad glow plug, open circuit, connector corrosion, bus bar resistance, controller channel problem.

Diagnostic order

Suggested workflow

  1. Confirm P0673 and identify the exact cylinder location.
  2. Test cylinder 3 glow plug resistance and compare with known-good cylinders.
  3. Verify preheat voltage reaches the circuit when commanded.
  4. Inspect connector fit, wiring integrity, and voltage drop under load.
  5. Repair the circuit or replace the failed component and verify startup quality improves.
Avoid guesswork

Common mistakes

  • Skipping cylinder identification and replacing the wrong plug.
  • Assuming the connector is fine because it is physically attached.
  • Ignoring the rest of the starting system when battery speed is already weak.
Repair path

Practical fix guidance

  • Correct the cylinder 3 plug or circuit fault found during resistance and voltage testing.
  • Address any connector corrosion so the repair does not come back with the next cold season.
  • Recheck for smoke, stumble, and crank time on a cold restart.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0673

Useful when the driver knows the wording but not the exact DTC yet.

  • cylinder 3 glow plug circuit
  • glow plug 3 open
  • cylinder 3 preheat fault
Related search intent

Queries this page can answer naturally

  • P0673 code meaning
  • what does P0673 mean
  • cylinder 3 glow plug symptoms
  • glow plug 3 open circuit
FAQ

Quick questions about P0673

Can P0673 come and go?

Yes. High resistance or intermittent connector issues can make the fault appear more in damp or cold conditions.

Does P0673 matter on a warm engine?

Much less. Glow plug faults usually show their value before and just after startup, not during normal warm driving.

Why compare resistance with the other glow plugs?

Because relative comparison often reveals whether one plug is clearly open or whether the issue is more likely in the shared wiring or control side.