P2685 moderate

Glow Plug 3 Circuit Open

The P2685 code means the vehicle's onboard diagnostic system has detected: Glow Plug 3 Circuit Open. This is a moderate severity code.

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Keep driving?
Short distances only
DIY difficulty
moderate
Estimated cost
$100 - $300 (parts and labor)
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Common Symptoms

  • Check Engine Light on
  • Cold-start difficulty increases
  • Rough idle for first minute of operation
  • Increased cranking time in winter
  • Exhaust smoke on cold start

Probable Causes (Ranked by Likelihood)

  • Glow plug 3 burned out or failed Very High
  • Wire break to glow plug 3 High
  • Corrosion at glow plug 3 electrical connection Moderate
  • Glow plug relay contact failure Low

Step-by-Step Diagnostic Procedure

  1. Read freeze frame data and confirm P2685 is present

  2. Measure glow plug 3 resistance with multimeter

  3. Check for voltage at glow plug 3 during glow cycle

  4. Inspect bus bar connection at glow plug rail

Frequently Asked Questions

What does P2685 mean?

P2685 indicates a problem with the glow plug 3 circuit open. Glow plugs are essential for cold-starting diesel engines by preheating the combustion chambers.

Can I drive with a P2685 code?

You can drive short distances once the engine is running. The main issue is cold starting difficulty. In warm weather, the effect is minimal, but cold weather starting will be significantly impacted.

How much does it cost to fix P2685?

Repairs typically cost $100 - $300. Individual glow plugs are $20 to $50 each, but labor can be significant if they are seized in the cylinder head.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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