AutoCodes – Generic – B2784

B2784 Code - Antenna Coil Open / Short

Quick Answer

When an open or short circuit is detected in the Transponder Key Amplifier Coil built into the Engine Switch, the Certification ECU (Smart Key ECU Assembly) stores this Diagnostic Trouble Code (DTC). Common causes include With Smart Key System, Faulty Engine Switch, Engine Switch harness is open or shorted. 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: B2784 indicates Antenna Coil Open / Short.
Common causes: Common causes include With Smart Key System, Faulty Engine Switch, Engine Switch harness is open or shorted.
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.

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Code Popularity 6,180

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 Jan 16, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B2784 Description

When an open or short circuit is detected in the Transponder Key Amplifier Coil built into the Engine Switch, the Certification ECU (Smart Key ECU Assembly) stores this Diagnostic Trouble Code (DTC). This DTC is also stored as a past DTC.
For vehicles without Smart Key System, when an open or short circuit is detected in the antenna coil built into the transponder key coil, the transponder key ECU assembly stores this DTC.

OBDII Code B2784 - Antenna Coil Open / Short - AutoCodes.com — B2784 Code - Antenna Coil Open / Short

What does this mean?

What are the Possible Causes of the DTC B2784?

With Smart Key System

Faulty Engine Switch
Engine Switch harness is open or shorted
Engine Switch circuit poor electrical connection
Faulty Certification ECU (Smart Key ECU Assembly)
Without Smart Key System
Faulty Transponder Key Coil
Transponder Key Coil harness is open or shorted
Transponder Key Coil circuit poor electrical connection
Faulty Transponder Key ECU Assembly

How to Fix the DTC B2784?

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 B2784 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 B2784 code?

Need more information on how to fix the B2784 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B2784 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B2784 Lexus — Antenna Coil Open / Short
B2784 Nissan — Electric Compressor Discharge Temperature Limit
B2784 Scion — Antenna Coil Open / Short
B2784 Toyota — Antenna Coil Open / Short

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 B2784 Code

1. What are the common symptoms of OBDII code B2784 (Antenna Coil Open / Short)?

The common symptoms include issues with keyless entry, remote start malfunction, and difficulty starting the vehicle.

2. What are the possible causes of OBDII code B2784?

The code B2784 can be caused by a faulty antenna coil, damaged wiring, poor electrical connections, or a malfunctioning key fob.

3. How can I diagnose the cause of OBDII code B2784?

Diagnosing the code involves checking the antenna coil for continuity, inspecting the wiring for damage, testing the key fob, and verifying electrical connections.

4. Can a DIY enthusiast repair OBDII code B2784 at home?

Some repairs related to OBDII code B2784, such as checking and replacing the antenna coil or repairing damaged wiring, can be done by a DIY enthusiast with the right tools and knowledge.

5. Is it safe to continue driving with OBDII code B2784 triggered?

While the vehicle may still be operable with the code triggered, it is recommended to address the issue promptly to prevent further problems with keyless entry and remote start functionality.

6. How much does it typically cost to repair OBDII code B2784?

The cost of repairing OBDII code B2784 can vary depending on the specific cause and the labor rates of the repair shop. Anticipate costs for parts and labor to address the issue.

7. Can a low car battery trigger OBDII code B2784?

Yes, a low car battery can potentially trigger OBDII code B2784 due to insufficient power supply affecting the antenna coil and key fob communication.

8. Are there any preventive measures to avoid OBDII code B2784 in the future?

Regularly inspecting the antenna coil, checking the key fob battery, and ensuring proper electrical connections can help prevent OBDII code B2784 from occurring.

9. Will resetting the OBDII system clear code B2784?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue such as a faulty antenna coil or damaged wiring is not addressed, the code is likely to return.

10. Can OBDII code B2784 affect other vehicle systems?

While OBDII code B2784 primarily relates to the antenna coil and keyless entry system, unresolved issues can potentially impact other vehicle systems that rely on proper signal transmission and connectivity.