OBD Guide

B166F

Right Trailer Tow Lamp Control Circuit Low

B166F is an OBD-II diagnostic trouble code meaning: Right Trailer Tow Lamp Control Circuit Low. Common causes: broken or damaged wiring harness to the right trailer lamp, oxidation of contacts in connectors. Estimated repair cost: $6–33.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$6–33 (est.)

Symptoms

  • Inoperative right trailer lamp
  • Error message on the dashboard
  • Circuit protection trip (if provided)

Causes

  • Broken or damaged wiring harness to the right trailer lamp
  • Oxidation of contacts in connectors
  • Burnt out lamp
  • Trailer control module malfunction
  • Short circuit in the circuit
  • Chain ground problems

How to Fix

  1. Check the condition of the right trailer lamp and replace if necessary
  2. Inspect the wiring harness for damage
  3. Check the contacts in the circuit connectors
  4. Measure the circuit resistance with a multimeter
  5. Check for voltage at the terminals of the trailer control module
  6. Check the condition of the chain mass

Related codes

FAQ

What does the B166F code mean?

B166F is an OBD-II diagnostic trouble code that indicates: Right Trailer Tow Lamp Control Circuit Low

What causes a B166F error code?

The most common causes of B166F include: Broken or damaged wiring harness to the right trailer lamp; Oxidation of contacts in connectors; Burnt out lamp; Trailer control module malfunction.

How do I fix a B166F diagnostic trouble code?

To fix B166F: Check the condition of the right trailer lamp and replace if necessary. Inspect the wiring harness for damage. Check the contacts in the circuit connectors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B166F?

Do not drive — repair immediately

How much does it cost to fix B166F?

The estimated repair cost for B166F is $6–33. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat