B0078 low

Right Fog Light Circuit Open

The B0078 code means the vehicle's onboard diagnostic system has detected: Right Fog Light Circuit Open. This is a low severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
easy
Estimated cost
$15 - $180 (parts and labor)
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Common Symptoms

  • Right fog light not illuminating
  • Asymmetric fog light pattern
  • Fog indicator on but right not working
  • Reduced fog visibility on right

Probable Causes (Ranked by Likelihood)

  • Burned out fog light bulb Very High
  • Corroded connector from road spray High
  • Damaged wiring at bumper Moderate
  • Failed fog light relay Low

Step-by-Step Diagnostic Procedure

  1. Inspect fog light bulb

  2. Check connector for corrosion

  3. Test voltage at socket

  4. Check relay and fuse

Frequently Asked Questions

What bulb do most fog lights use?

Common types: H11, H8, H16, 9006, and 5202.

Can I upgrade to LED?

LED replacements are available for most halogen fog lights.

Should fog lights be aimed differently?

Yes, aimed low and wide to illuminate road surface without blinding oncoming drivers.

Sources

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

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