Engine-CodesBuick – P0440 Buick

P0440 Buick Code - Evaporative Emission System

Quick Answer

The P0440 code for Buick vehicles relates to the Evaporative Emission System. Common causes include Loose or damaged fuel cap, Faulty purge or vent valve, Cracked or damaged hoses. 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
P0440 Buick indicates Evaporative Emission System.
Common causes
Common causes include Loose or damaged fuel cap, Faulty purge or vent valve, Cracked or damaged hoses.
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.
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0440 Buick Description

The P0440 code for Buick vehicles relates to the Evaporative Emission System. This system is designed to prevent harmful fuel vapors from escaping into the atmosphere by storing and then purging them within the charcoal canister. When this code is triggered, it indicates a problem with the system's ability to properly control and monitor fuel vapors. This can lead to increased emissions, decreased fuel efficiency, and potentially even engine performance issues.

OBDII Code P0440 Buick - Evaporative Emission System
P0440 Buick Code - Evaporative Emission System

Common Causes of P0440 Buick

  1. Loose or damaged fuel cap
  2. Faulty purge or vent valve
  3. Cracked or damaged hoses
  4. Charcoal canister saturation
  5. Electrical issues with sensors or wiring

Symptoms of P0440 Buick

  1. Check Engine Light illuminated
  2. Strong fuel odor
  3. Decreased fuel efficiency
  4. Rough idling or stalling
  5. Failed emissions test

How to Fix P0440 Buick

  1. Check and tighten or replace fuel cap
  2. Inspect and replace purge or vent valve if faulty
  3. Check and repair or replace damaged hoses
  4. Test and replace charcoal canister if saturated
  5. Diagnose and repair any electrical issues with sensors or wiring

Cost to Fix P0440 Buick

The cost of repairing a P0440 code on a Buick can vary depending on the specific cause of the issue and the labor rates in your area. In general, the cost can range from $100 to $500, including parts and labor. Keep in mind that additional diagnostic time may be required to pinpoint the exact cause of the problem. It is recommended to get quotes from local auto repair shops to get a more accurate estimate based on your vehicle's make and model.

Tech Notes for P0440 Buick

The P0440 code means that the control module has detected a leak in the Evaporative Emission (EVAP). Loose fuel tank filler cap is the most common cause that triggers the P0440 code.

When is the Code Detected?

The Evaporative Emission (EVAP) system is not able to build vacuum

Need more information about the P0440 Buick 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 P0440 Buick Code

No Frequently Asked Questions about P0440 Buick Code found.

Discuss the causes and fixes for P0440 Buick OBDII Code

  • 2013 Verano 55400 miles the PO440 code came on the code reader. Mechanic said the oil is probably contaminated and when I get the oil changed tell the company to use bottled oil not bulk. I just had the oil changed and told him so then he said it is probably the sensor needs to be changed he looked it up for cost and said that both seniors had be changed at same time they cost 89.00 each and 90.00 labor. Did not have them changed at this point.

  • First of all, the P0440 code has nothing to do with engine oil, and if the oil is bottle or in a drum does not change anything.

    Do no change anything yet, just make sure the gas cap is tight and then clear the code. You can clear the code with a OBDII scanner or by disconnecting the car battery for about 30 minutes.

  • Ok thank you for the info