AutoCodes – Scion – P0503 Scion

P0503 Scion Code - Vehicle Speed Sensor 'A' Intermittent / Erratic / High

Quick Answer

Vehicles, which are equipped with ABS (Anti-lock Brake System), detect the vehicle speed using the Skid Control ECU (Brake Actuator Assembly) and speed sensor. Common causes include Faulty Vehicle Speed Sensor, Vehicle speed sensor harness or connectors is open or shorted, Vehicle speed 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: P0503 Scion indicates Vehicle Speed Sensor 'A' Intermittent / Erratic / High.
Common causes: Common causes include Faulty Vehicle Speed Sensor, Vehicle speed sensor harness or connectors is open or shorted, Vehicle speed 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 2,993

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 01, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0503 Scion Description

Vehicles, which are equipped with ABS (Anti-lock Brake System), detect the vehicle speed using the Skid Control ECU (Brake Actuator Assembly) and speed sensor. The speed sensor monitors the wheel rotation speed and sends a signal to the Skid Control ECU. The Skid Control ECU converts the wheel speed signal into a 4-pulse signal and transmits it to the Engine Control Module (ECM) via the combination meter assembly. The ECM determines the vehicle speed based on the frequency of the pulse signal.
If a malfunction (a rapid change in vehicle speed) in the vehicle speed signal being output from the brake actuator assembly (skid control ECU) is detected while the cruise control is in operation, the ECM determines there to be a momentary interruption or noise and stores a Diagnostic Trouble Code (DTC).

OBDII Code P0503 Scion - Vehicle Speed Sensor 'A' Intermittent / Erratic / High - AutoCodes.com — P0503 Scion Code - Vehicle Speed Sensor 'A' Intermittent / Erratic / High

What does this mean?

What are the Possible Causes of the DTC P0503 Scion?

Faulty Vehicle Speed Sensor
Vehicle speed sensor harness or connectors is open or shorted
Vehicle speed sensor circuit poor electrical connection
Faulty Combination Meter Assembly
Faulty Engine Control Module (ECM)

How to Fix the DTC P0503 Scion?

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 P0503 Scion 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.