AutoCodes – Generic – C1121

C1121 Code - Front Left Output ABS Solenoid

Quick Answer

The control unit computes the wheel rotating speed by the signal sent from the sensor. Common causes include Faulty ABS Actuator/Electric Unit, ABS Actuator/Electric Unit harness is open or shorted, ABS Actuator/Electric Unit 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: C1121 indicates Front Left Output ABS Solenoid.
Common causes: Common causes include Faulty ABS Actuator/Electric Unit, ABS Actuator/Electric Unit harness is open or shorted, ABS Actuator/Electric Unit 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 11,863

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 Aug 16, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code C1121 Description

The control unit computes the wheel rotating speed by the signal sent from the sensor. Then it supplies a DC current to the actuator solenoid valve. It also controls ON-OFF operation of the solenoid valve relay and motor relay. If any electrical malfunction should be detected in the system, the control unit causes the warning lamp to turn on. In this condition, the ABS will be deactivated by the control unit, and the vehicle's brake system reverts to normal operation.
The ABS actuator and electric unit (control unit) contains: An electric motor and pump, Two relays, Eight solenoid valves ( each inlet and outlet for LH front, RH front, LH rear, RH rear), and ABS control unit.
These components control the hydraulic circuit that increases, holds or decreases hydraulic pressure to all or individual wheels. The ABS actuator and electric unit (control unit) cannot be disassembled and must be replaced as an assembly.

OBDII Code C1121 - Front Left Output ABS Solenoid - AutoCodes.com — C1121 Code - Front Left Output ABS Solenoid

What does this mean?

What are the Possible Causes of the DTC C1121?

Faulty ABS Actuator/Electric Unit
ABS Actuator/Electric Unit harness is open or shorted
ABS Actuator/Electric Unit poor electrical connection

How to Fix the DTC C1121?

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 does this mean?

Code Tech Notes

The ABS has an electronic control unit to control major functions. The control unit accepts input signals from sensors and controls operation of the actuator. It is also important to check for conventional problems such as air leaks in the booster or lines, lack of brake fluid, or other problems with the brake system.
It is much more difficult to diagnose a problem that occurs intermittently rather than continuously. Most intermittent problems are caused by poor electrical connections or faulty wiring. In this case, careful checking of suspicious circuits may help prevent the replacement of good parts.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C1121 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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Information for Specific Makes

C1121 Infiniti — Front Left Output ABS Solenoid
C1121 Nissan — Front Left Output ABS Solenoid

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.