OBD Guide
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B12C5

Engine Start/Stop Switch Failure

B12C5 is an OBD-II diagnostic trouble code meaning: Engine Start/Stop Switch Failure. Common causes: mechanical damage to the start/stop button, open/short circuit in wiring harness. Estimated repair cost: $33–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–167 (est.)

Symptoms

  • The engine does not start when the button is pressed
  • The motor does not stop when the button is pressed
  • Start/Stop button indicator blinking
  • Check Engine Light Illuminates

Causes

  • Mechanical damage to the Start/Stop button
  • Open/short circuit in wiring harness
  • Relay or fuse problems
  • Control unit malfunction
  • Low battery voltage

How to Fix

  1. Check the condition of the Start/Stop button for mechanical damage
  2. Check the integrity of the wiring harness to the button
  3. Check battery voltage
  4. Check relays and fuses
  5. Read control unit parameters
  6. If necessary, replace the button or wiring harness

Related codes

B12C0B12C1B12C6

FAQ

What does the B12C5 code mean?

B12C5 is an OBD-II diagnostic trouble code that indicates: Engine Start/Stop Switch Failure

What causes a B12C5 error code?

The most common causes of B12C5 include: Mechanical damage to the Start/Stop button; Open/short circuit in wiring harness; Relay or fuse problems; Control unit malfunction.

How do I fix a B12C5 diagnostic trouble code?

To fix B12C5: Check the condition of the Start/Stop button for mechanical damage. Check the integrity of the wiring harness to the button. Check battery voltage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B12C5?

Limited driving only, diagnose soon

How much does it cost to fix B12C5?

The estimated repair cost for B12C5 is $33–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat