AutoCodes – Nissan – U0121 Nissan

U0121 Nissan Code - Lost Communication With Anti-Lock Brake System Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Anti-Lock Brake System (ABS) Control Module, Anti-Lock Brake System Control Module harness is open or shorted, Anti-Lock Brake System Control Module 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: U0121 Nissan indicates Lost Communication With Anti-Lock Brake System Control Module .
Common causes: Common causes include Faulty Anti-Lock Brake System (ABS) Control Module, Anti-Lock Brake System Control Module harness is open or shorted, Anti-Lock Brake System Control Module 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.

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Code Popularity 5,098

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 Apr 06, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0121 Nissan Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Anti-Lock Brake System (ABS) Control Module has not been received.

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OBDII Code U0121 Nissan - Lost Communication With Anti-Lock Brake System Control Module - AutoCodes.com — U0121 Nissan Code - Lost Communication With Anti-Lock Brake System Control Module

What does this mean?

What are the Possible Causes of the DTC U0121 Nissan?

Faulty Anti-Lock Brake System (ABS) Control Module
Anti-Lock Brake System Control Module harness is open or shorted
Anti-Lock Brake System Control Module circuit poor electrical connection

How to Fix the DTC U0121 Nissan?

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 U0121 Nissan 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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Need more information on how to fix the U0121 Nissan code? Get Access to Factory Service Manuals

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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 U0121 Nissan Code

1. What are the common symptoms of OBDII code U0121 in a Nissan related to the Anti-Lock Brake System Control Module?

- Common symptoms include the ABS warning light coming on, loss of communication with the ABS system, potential traction control issues, and difficulty braking.

2. What are some possible causes of the U0121 code indicating a lost communication with the Anti-Lock Brake System Control Module in a Nissan?

- Possible causes may include a faulty ABS control module, damaged ABS wiring harness, corroded connectors, blown fuses, or a malfunctioning ABS wheel speed sensor.

3. How can I diagnose the U0121 code in a Nissan indicating a lost communication with the ABS control module?

- Diagnosis typically involves using an OBDII scanner to read the code, checking for other related codes, inspecting the ABS system wiring and connectors, testing the ABS control module, and verifying sensor functionality.

4. Is it safe to drive my Nissan with the U0121 code related to the ABS control module communication issue?

- It is not recommended to drive your vehicle with the U0121 code present, as it may affect the proper functioning of the ABS system, potentially compromising your safety on the road.

5. Can I reset the U0121 code in my Nissan to see if it comes back, or should I address the issue immediately?

- While you can try clearing the code temporarily, it is crucial to address the underlying issue causing the communication loss with the ABS control module to prevent potential safety hazards.

6. Are there any DIY repair tips for fixing the U0121 code related to the lost communication with the ABS control module in a Nissan?

- DIY repair tips may include checking and cleaning the ABS system connectors, inspecting the wiring for damage, ensuring proper grounding, and testing the ABS control module for functionality.

7. How much does it typically cost to repair the U0121 code indicating a lost communication with the ABS control module in a Nissan?

- Repair costs can vary depending on the exact cause of the issue, but expenses may include parts replacement, wiring repairs, labor costs, and potential diagnostic fees from a mechanic or dealership.

8. Can a simple battery disconnect reset the U0121 code in a Nissan, or is a more in-depth reset procedure required?

- A battery disconnect may temporarily clear the code, but if the underlying issue causing the ABS communication problem persists, the code is likely to reappear once the system is back online.

9. Will fixing the U0121 code related to the ABS control module communication problem improve the overall performance of my Nissan's braking system?

- Yes, addressing the U0121 code promptly and effectively will restore proper communication with the ABS control module, ensuring the optimal performance and safety of your vehicle's braking system.

10. Should I seek professional help to diagnose and repair the U0121 code indicating a lost communication with the Anti-Lock Brake System Control Module in my Nissan?

- It is recommended to consult a qualified mechanic or dealership to accurately diagnose and repair the U0121 code, as issues with the ABS system are crucial for vehicle safety and require specialized knowledge and tools.