OBD Guide

B3121

Keyless Entry Antenna 3

B3121 is an OBD-II diagnostic trouble code meaning: Keyless Entry Antenna 3. Common causes: broken or damaged antenna wires, malfunction of the antenna itself. Estimated repair cost: $56–167.

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

Symptoms

  • Reducing the range of the key fob
  • Problems with unlocking/locking doors
  • Sometimes the system stops working completely

Causes

  • Broken or damaged antenna wires
  • Malfunction of the antenna itself
  • Wiring Harness Problems
  • Today we will discuss some common issues related to B3121 and their solutions.
  • Malfunctions of the keyless entry module

How to Fix

  1. Check the integrity of the antenna wires and contacts
  2. Test the antenna using diagnostic equipment
  3. Replace the antenna if a malfunction is detected
  4. Check the operation of the keyless entry module

Related codes

Error B3121 by Vehicle Brand

FAQ

What does the B3121 code mean?

B3121 is an OBD-II diagnostic trouble code that indicates: Keyless Entry Antenna 3

What causes a B3121 error code?

The most common causes of B3121 include: Broken or damaged antenna wires; Malfunction of the antenna itself; Wiring Harness Problems; Today we will discuss some common issues related to B3121 and their solutions..

How do I fix a B3121 diagnostic trouble code?

To fix B3121: Check the integrity of the antenna wires and contacts. Test the antenna using diagnostic equipment. Replace the antenna if a malfunction is detected. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B3121?

Limited driving only, diagnose soon

How much does it cost to fix B3121?

The estimated repair cost for B3121 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat