AutoCodes – Generic – B3120

B3120 Code - Keyless Entry Antenna 2

Quick Answer

The passenger front door handle antenna is located in the passenger front door handle assembly and is used to establish low frequency communications with the keyless entry transmitter. Common causes include Faulty Passenger Exterior Door Handle Assembly, Passenger Exterior Door Handle Assembly harness is open or shorted, Passenger Exterior Door Handle Assembly circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B3120 indicates Keyless Entry Antenna 2.
Common causes: Common causes include Faulty Passenger Exterior Door Handle Assembly, Passenger Exterior Door Handle Assembly harness is open or shorted, Passenger Exterior Door Handle Assembly circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 3,838

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code B3120 Description

The passenger front door handle antenna is located in the passenger front door handle assembly and is used to establish low frequency communications with the keyless entry transmitter. As a vehicle with locked doors is approached with a keyless entry transmitter and the exterior door handle button is pressed, the Keyless Entry Control Module communicates with the passenger front door handle keyless entry antenna. The Diagnostic Trouble Code (DTC) sets when the keyless entry control module detects a short to ground on the passenger front door keyless entry antenna signal circuit.

OBDII Code B3120 - Keyless Entry Antenna 2 - AutoCodes.com — B3120 Code - Keyless Entry Antenna 2

What does this mean?

What are the Possible Causes of the DTC B3120?

Faulty Passenger Exterior Door Handle Assembly
Passenger Exterior Door Handle Assembly harness is open or shorted
Passenger Exterior Door Handle Assembly circuit poor electrical connection
Faulty Keyless Entry Control Module

How to Fix the DTC B3120?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3120 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B3120 code?

Need more information on how to fix the B3120 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3120 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B3120 Buick — Keyless Entry Antenna 2
B3120 Cadillac — Keyless Entry Antenna 2
B3120 Chevrolet — Keyless Entry Antenna 2
B3120 GMC — Keyless Entry Antenna 2

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B3120 Code

1. What does OBDII code B3120 mean?

Code B3120 indicates an issue with Keyless Entry Antenna 2, which is responsible for transmitting or receiving signals for the keyless entry system in your vehicle.

2. What are the symptoms of code B3120?

Common symptoms include the keyless entry system not working, difficulty unlocking or locking the vehicle remotely, or the car not detecting the key fob.

3. What causes code B3120 to appear?

Causes can include a faulty keyless entry antenna, damaged wiring or connections, a malfunctioning key fob, or interference from other electronic devices.

4. How is code B3120 diagnosed?

A technician will inspect the keyless entry antenna, check the wiring and connectors for damage, and test the key fob to ensure it's functioning properly.

5. Can I still drive my car with code B3120?

Yes, you can still drive the car, but the keyless entry system may not work correctly, which could be inconvenient.

6. How do you fix code B3120?

Repairs may involve replacing the faulty keyless entry antenna, repairing damaged wiring, or reprogramming the key fob.

7. How much does it cost to fix code B3120?

Repair costs vary but can range from $100 to $400 depending on whether the issue is with the antenna, wiring, or key fob.

8. Can a dead key fob battery cause code B3120?

A dead key fob battery is unlikely to trigger code B3120 directly, but it can prevent the keyless entry system from functioning, which could be mistaken for an antenna issue.

9. Is code B3120 specific to certain car brands?

Code B3120 is a generic code but may be more commonly associated with certain manufacturers that use multiple keyless entry antennas in their systems.

10. Can interference from other electronics trigger code B3120?

Yes, interference from devices like cell phones or other wireless signals can occasionally disrupt the keyless entry antenna signal, potentially contributing to this issue.