AutoCodes – Buick – P0446 Buick

P0446 Buick Code - Evaporative Emission Vent System Performance

Quick Answer

This Diagnostic Trouble Code (DTC) tests the Evaporative Emission (EVAP) system for a restricted or blocked EVAP vent path that would cause excess amounts of vacuum to be developed in the EVAP system. Common causes include Plugged vapor canister, Pinched or blocked EVAP hose, Faulty Evaporative Emission Vent Solenoid Valve. 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: P0446 Buick indicates Evaporative Emission Vent System Performance.
Common causes: Common causes include Plugged vapor canister, Pinched or blocked EVAP hose, Faulty Evaporative Emission Vent Solenoid Valve.
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 40,127

How popular is this code, among other codes? Medium

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 Jul 21, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0446 Buick Description

This Diagnostic Trouble Code (DTC) tests the Evaporative Emission (EVAP) system for a restricted or blocked EVAP vent path that would cause excess amounts of vacuum to be developed in the EVAP system. The Engine Control Module (ECM) commands the EVAP purge solenoid valve Open and the EVAP vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the ECM commands the EVAP purge solenoid valve Closed and the EVAP vent solenoid valve Open. The ECM monitors the Fuel Tank Pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 in H2O in a calibrated time, this DTC sets.

OBDII Code P0446 Buick - Evaporative Emission Vent System Performance - AutoCodes.com — P0446 Buick Code - Evaporative Emission Vent System Performance

What does this mean?

What are the Possible Causes of the DTC P0446 Buick?

Plugged vapor canister
Pinched or blocked EVAP hose
Faulty Evaporative Emission Vent Solenoid Valve
Evaporative Emission Vent Solenoid Valve harness is open or shorted
Evaporative Emission Vent Solenoid Valve circuit poor electrical connection
Faulty Fuel Tank Pressure (FTP) sensor

How to Fix the DTC P0446 Buick?

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

Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0446 Buick 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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Need Help with the 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.

Frequently Asked Questions about P0446 Buick Code

1. What are the common symptoms of OBDII code P0446 in a Buick related to the Evaporative Emission Vent System Performance?

- Common symptoms include the check engine light illuminating, possible fuel odor near the vehicle, and failed emission tests.

2. What are the typical causes of the P0446 code in a Buick?

- The common causes include a faulty vent valve, a blocked vent filter, damaged vacuum hoses, or an issue with the EVAP system purge operation.

3. How can I diagnose the P0446 code in my Buick?

- Diagnosis involves checking the condition of the vent valve, inspecting the vent filter, examining vacuum hoses for leaks or damage, and testing the purge solenoid operation.

4. What are the potential dangers of ignoring the P0446 code in a Buick?

- Ignoring the code may lead to increased emissions, reduced fuel efficiency, and potential damage to other components in the EVAP system over time.

5. How can I fix the P0446 code in my Buick?

- Repair options may include replacing the vent valve, cleaning or replacing the vent filter, repairing or replacing damaged vacuum hoses, or addressing issues with the purge solenoid.

6. Can I reset the check engine light after fixing the P0446 code in my Buick?

- Yes, after repairing the issue causing the code, you can reset the check engine light using an OBDII scanner or by disconnecting the car's battery for a few minutes.

7. Is it safe to drive my Buick with the P0446 code present?

- While the vehicle may still be operable with the code, it is recommended to address the issue promptly to prevent potential long-term problems and ensure proper emissions control.

8. What is the role of the Evaporative Emission Vent System in a Buick?

- The Evaporative Emission Vent System helps control and store fuel vapors from the fuel tank, preventing them from being released into the atmosphere.

9. How do I prevent the P0446 code from recurring in my Buick?

- Regular maintenance, such as checking and replacing worn hoses, inspecting the vent valve, and keeping the EVAP system clean, can help prevent the code from reappearing.

10. Can a DIY enthusiast fix the P0446 code issue in a Buick, or is professional help recommended?

- Depending on your skills and knowledge, some repairs related to the P0446 code can be done at home. However, if you are unsure or uncomfortable, seeking professional help is advisable to ensure the issue is properly resolved.