AutoCodes – Generic – P1938

P1938 Code - Brake Switch/Sensor Signal

Quick Answer

P1938 indicates Brake Switch/Sensor Signal. Common causes include Faulty Brake Switch/Sensor, Brake Switch/Sensor harness is open or shorted, Brake Switch/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: P1938 indicates Brake Switch/Sensor Signal.
Common causes: Common causes include Faulty Brake Switch/Sensor, Brake Switch/Sensor harness is open or shorted, Brake Switch/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 3,792

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 Sep 29, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1938 Description

OBDII Code P1938 - Brake Switch/Sensor Signal - AutoCodes.com — P1938 Code - Brake Switch/Sensor Signal

What does this mean?

What are the Possible Causes of the DTC P1938?

Faulty Brake Switch/Sensor
Brake Switch/Sensor harness is open or shorted
Brake Switch/Sensor circuit poor electrical connection

How to Fix the DTC P1938?

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 P1938 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 P1938 code?

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Need Help with the Code?

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Information for Specific Makes

P1938 Ford — Brake Switch/Sensor Signal
P1938 Lincoln — Brake Switch/Sensor Signal
P1938 Mazda — Brake Switch/Sensor Signal
P1938 Mercury — Brake Switch/Sensor Signal

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.