AutoCodes – Lexus – B1242 Lexus

B1242 Lexus Code - Wireless Door Lock Tuner Circuit Malfunction

Quick Answer

The Door Control Receiver is used to receive radio waves related to the entry functions of the electrical key transmitter sub-assembly. Common causes include Faulty Door Control Receiver, Door Control Receiver harness is open or shorted, Door Control Receiver circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B1242 Lexus indicates Wireless Door Lock Tuner Circuit Malfunction.
Common causes: Common causes include Faulty Door Control Receiver, Door Control Receiver harness is open or shorted, Door Control Receiver circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 6,650

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 19, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1242 Lexus Description

The Door Control Receiver is used to receive radio waves related to the entry functions of the electrical key transmitter sub-assembly. The certification ECU (smart key ECU assembly) decodes the requested electrical key transmitter sub-assembly operation by identifying a key code based on the radio waves received via the door control receiver. The door control receiver receives a signal from the electrical key transmitter sub-assembly and sends signals to the main body ECU (multiplex network body ECU) through the certification ECU (smart key ECU assembly). (For example, if a door lock operation is requested, the certification ECU [smart key ECU assembly] sends a door lock command to the main body ECU [multiplex network body ECU]).

OBDII Code B1242 Lexus - Wireless Door Lock Tuner Circuit Malfunction - AutoCodes.com — B1242 Lexus Code - Wireless Door Lock Tuner Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC B1242 Lexus?

Faulty Door Control Receiver
Door Control Receiver harness is open or shorted
Door Control Receiver circuit poor electrical connection
Faulty Certification ECU (Smart Key ECU Assembly)

How to Fix the DTC B1242 Lexus?

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 B1242 Lexus 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.

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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 B1242 Lexus Code

1. What does the OBDII code B1242 indicate on a Lexus?

The B1242 code on a Lexus indicates a malfunction in the wireless door lock tuner circuit. This circuit is involved in the operation of the vehicle's remote keyless entry system.

2. What are common symptoms of the B1242 code in a Lexus?

Symptoms may include the remote keyless entry system not working, the doors not locking/unlocking with the remote, and sometimes an indicator light on the dashboard.

3. What could cause a B1242 code to appear on a Lexus?

Causes can include faulty door lock receiver, poor electrical connections, damaged wiring within the door lock circuit, or a malfunctioning control module.

4. How is the B1242 code diagnosed in a Lexus?

Diagnosis involves using a scan tool to confirm the presence of the code, visually inspecting the wiring and connections of the door lock system, and testing the door lock receiver and related components with a multimeter.

5. What are the steps to fix the B1242 code on a Lexus?

Repair steps may include replacing the defective door lock receiver, repairing or replacing damaged wiring, securing loose connections, or resetting the vehicleâ€™s control module.

6. Can I drive my Lexus with the B1242 code active?

While you can still drive your vehicle, the functionality of the remote keyless entry may be impaired. It is advisable to address the issue promptly to restore full functionality and security features.

7. Is the B1242 code a sign of a bigger electrical problem in my Lexus?

The B1242 code specifically relates to the tuner circuit of the wireless door lock system. While it is not necessarily indicative of a larger electrical issue, unresolved problems in one circuit can sometimes lead to problems in related systems.

8. What tools are needed to diagnose the B1242 code on a Lexus?

Tools needed may include a professional OBDII scanner, a digital multimeter for electrical testing, and basic hand tools for accessing the circuit components.

9. How much does it typically cost to repair a B1242 code on a Lexus?

Costs can vary widely depending on the specific repair required and the rates of the service provider. Minor repairs like reconnecting loose wires or replacing fuses are less expensive, while replacing a faulty door lock receiver or control module can be more costly.