OBD Guide

C1118

Trailer Brake Control Sensitivity Switch Circuit Malfunction

C1118 is an OBD-II diagnostic trouble code meaning: Trailer Brake Control Sensitivity Switch Circuit Malfunction. Common causes: open or short circuit in wiring harness, oxidation of switch contacts. Estimated repair cost: $56–167.

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

Symptoms

  • Trailer brake sensitivity switch not working
  • Unstable trailer braking
  • Malfunction indicator light comes on

Causes

  • Open or short circuit in wiring harness
  • Oxidation of switch contacts
  • Sensitivity switch malfunction
  • Problems with the trailer brake control unit

How to Fix

  1. Check the integrity of the wiring harness
  2. Clean switch contacts
  3. Test sensitivity switch
  4. Replace switch if necessary
  5. Check the operation of the trailer brake control unit

Related codes

FAQ

What does the C1118 code mean?

C1118 is an OBD-II diagnostic trouble code that indicates: Trailer Brake Control Sensitivity Switch Circuit Malfunction

What causes a C1118 error code?

The most common causes of C1118 include: Open or short circuit in wiring harness; Oxidation of switch contacts; Sensitivity switch malfunction; Problems with the trailer brake control unit.

How do I fix a C1118 diagnostic trouble code?

To fix C1118: Check the integrity of the wiring harness. Clean switch contacts. Test sensitivity switch. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1118?

Limited driving only, diagnose soon

How much does it cost to fix C1118?

The estimated repair cost for C1118 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat