AutoCodes – Lexus – C120B Lexus

C120B Lexus Code - Ignition Supply Voltage Low

Quick Answer

The Diagnostic Trouble Code (DTC) will be set when the Master Cylinder Pressure Sensor power supply voltage decrease occurs, or a history of voltage decrease exists, and defective Master Cylinder Pressure Sensor output continues for 1 second or more. Common causes include Faulty Master Cylinder Pressure Sensor, Master Cylinder Pressure Sensor harness is open or shorted, Master Cylinder Pressure Sensor 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: C120B Lexus indicates Ignition Supply Voltage Low.
Common causes: Common causes include Faulty Master Cylinder Pressure Sensor, Master Cylinder Pressure Sensor harness is open or shorted, Master Cylinder Pressure Sensor 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 304

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jan 18, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
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Code C120B Lexus Description

OBDII Code C120B Lexus - Ignition Supply Voltage Low - AutoCodes.com — C120B Lexus Code - Ignition Supply Voltage Low

What does this mean?

What are the Possible Causes of the DTC C120B Lexus?

Faulty Master Cylinder Pressure Sensor
Master Cylinder Pressure Sensor harness is open or shorted
Master Cylinder Pressure Sensor circuit poor electrical connection
Faulty Skid Control ECU (Brake Actuator Assembly)

How to Fix the DTC C120B 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 C120B 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.

Need more information about the C120B Lexus code?

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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.