OBD Guide
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B257A

Headlamp Switch Input Signals Correlation Malfunction

B257A is an OBD-II diagnostic trouble code meaning: Headlamp Switch Input Signals Correlation Malfunction. Common causes: headlight switch malfunction, wiring harness damage. Estimated repair cost: $56–167.

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

Symptoms

  • Incorrect operation of headlights
  • Headlights flash when turned on
  • Lack of response to switching lighting modes

Causes

  • Headlight switch malfunction
  • Wiring harness damage
  • Short circuit in the circuit
  • Lighting control module malfunction

How to Fix

  1. Check the headlight switch for mechanical damage
  2. Check the integrity of the wiring harness and connectors
  3. Check the voltage in the headlight switch circuit
  4. Scan the lighting control module for errors
  5. If necessary, replace the headlight switch or wiring harness.

Related codes

B257BB257CB257D

FAQ

What does the B257A code mean?

B257A is an OBD-II diagnostic trouble code that indicates: Headlamp Switch Input Signals Correlation Malfunction

What causes a B257A error code?

The most common causes of B257A include: Headlight switch malfunction; Wiring harness damage; Short circuit in the circuit; Lighting control module malfunction.

How do I fix a B257A diagnostic trouble code?

To fix B257A: Check the headlight switch for mechanical damage. Check the integrity of the wiring harness and connectors. Check the voltage in the headlight switch circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B257A?

Limited driving only, diagnose soon

How much does it cost to fix B257A?

The estimated repair cost for B257A is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat