OBD Guide
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B1278

Headlight Switch ON Position Circuit Malfunction

B1278 is an OBD-II diagnostic trouble code meaning: Headlight Switch ON Position Circuit Malfunction. Common causes: faulty headlight switch, open or short circuit in wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Headlights do not turn on in ON position
  • Flashing headlights
  • Incorrect operation of automatic headlights
  • The malfunction indicator on the dashboard is on

Causes

  • Faulty headlight switch
  • Open or short circuit in wiring harness
  • Contact corrosion
  • Faulty headlight relay
  • Problems with the control unit

How to Fix

  1. Check the headlight switch for malfunctions
  2. Inspect the wiring harness for damage
  3. Check contacts for corrosion
  4. Replace headlight relay if necessary
  5. Test the control unit

Related codes

B1279B1280B1281

FAQ

What does the B1278 code mean?

B1278 is an OBD-II diagnostic trouble code that indicates: Headlight Switch ON Position Circuit Malfunction

What causes a B1278 error code?

The most common causes of B1278 include: Faulty headlight switch; Open or short circuit in wiring harness; Contact corrosion; Faulty headlight relay.

How do I fix a B1278 diagnostic trouble code?

To fix B1278: Check the headlight switch for malfunctions. Inspect the wiring harness for damage. Check contacts for corrosion. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1278?

Limited driving only, diagnose soon

How much does it cost to fix B1278?

The estimated repair cost for B1278 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat