AutoCodes – Scion – P0451 Scion

P0451 Scion Code - Evaporative Emission Control System Pressure Sensor Range / Performance

Quick Answer

5 hours after the ignition switch is turned off, the leak detection pump creates negative pressure (vacuum) in the Evaporative Emission (EVAP) system. Common causes include Faulty Canister Pump Module, Canister Pump Module harness is open or shorted, Canister Pump Module circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: P0451 Scion indicates Evaporative Emission Control System Pressure Sensor Range / Performance.
Common causes: Common causes include Faulty Canister Pump Module, Canister Pump Module harness is open or shorted, Canister Pump Module circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 10,396

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 26, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0451 Scion Description

5 hours after the ignition switch is turned off, the leak detection pump creates negative pressure (vacuum) in the Evaporative Emission (EVAP) system. The Engine Control Module (ECM) monitors for leaks and actuator malfunctions based on the EVAP pressure. The leak detection pump creates negative pressure through the reference orifice. When the system is normal, the EVAP pressure is between 97 to 100 kPa(abs) [726 to 750 mmHg(abs) (Typical value)] and saturated within a minute. If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the canister pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the Diagnostic Trouble Code (DTC).
Alternatively, if the sensor voltage output does not change for 2 minutes, the ECM interprets this as the sensor being stuck, and stops the monitor. The ECM then illuminates the MIL and stores the DTC.
The Canister Pump Module is attached to the EVAP Canister and contains the Canister Pressure Sensor, the Leak Detection Pump, and the Vent Valve.

OBDII Code P0451 Scion - Evaporative Emission Control System Pressure Sensor Range / Performance - AutoCodes.com — P0451 Scion Code - Evaporative Emission Control System Pressure Sensor Range / Performance

What does this mean?

What are the Possible Causes of the DTC P0451 Scion?

Faulty Canister Pump Module
Canister Pump Module harness is open or shorted
Canister Pump Module circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0451 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 P0451 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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Information for Specific Scion Models

P0451 2005 Scion xB — EVAP System Pressure Sensor Range/Performance
P0451 2006 Scion xB — EVAP System Pressure Sensor Range/Performance
P0451 2007 Scion xB — EVAP System Pressure Sensor Range/Performance

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.