OBD Guide

P0678

Cylinder 8 Glow Plug Circuit/Open

P0678 is an OBD-II diagnostic trouble code meaning: Cylinder 8 Glow Plug Circuit/Open. Common causes: burnt-out glow plug for cylinder 8, broken power wire. Estimated repair cost: $22–67.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$22–67 (est.)

Symptoms

  • Difficulty starting a diesel engine in cold weather
  • Check Engine Light
  • White smoke on cold start
  • Unstable engine operation after starting
  • Glow plug indicator on the dashboard

Causes

  • Burnt-out glow plug for cylinder 8
  • Broken power wire
  • Oxidation or poor contact in the connector
  • GPCM module malfunction
  • Wiring damage

How to Fix

  1. Read OBD-II error codes
  2. Measure the resistance of the spark plug of cylinder 8 (standard: 0.5–2 Ohm)
  3. Inspect the wiring and spark plug connector
  4. Check the supply voltage at the spark plug terminal
  5. Replace a faulty glow plug
  6. If the error occurs again, check GPCM

Related codes

Error P0678 by Vehicle Brand

FAQ

What does the P0678 code mean?

P0678 is an OBD-II diagnostic trouble code that indicates: Cylinder 8 Glow Plug Circuit/Open

What causes a P0678 error code?

The most common causes of P0678 include: Burnt-out glow plug for cylinder 8; Broken power wire; Oxidation or poor contact in the connector; GPCM module malfunction.

How do I fix a P0678 diagnostic trouble code?

To fix P0678: Read OBD-II error codes. Measure the resistance of the spark plug of cylinder 8 (standard: 0.5–2 Ohm). Inspect the wiring and spark plug connector. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0678?

Yes, but get it checked soon

How much does it cost to fix P0678?

The estimated repair cost for P0678 is $22–67. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat