P1440 – Purge Valve Stuck Open

Understanding the P1440 Engine Fault Code

The P1440 is a manufacturer-specific powertrain code that indicates a problem with the evaporative emission (EVAP) system, specifically that the purge valve is stuck open. This code is commonly seen on Nissan, Honda, Chevrolet and other vehicles.

Is it safe to drive with a P1440 code?

In most cases, you can continue driving safely with a P1440 code for a short time. However, it's best to diagnose and fix the issue promptly to prevent potential problems:

• Increased emissions
• Reduced fuel economy
• Difficulty starting the engine
• Rough idle or stalling

If the check engine light is flashing, this indicates a severe misfire that can damage the catalytic converter. In this case, pull over and have the vehicle towed to avoid costly repairs.

EVAP System Overview

The EVAP system prevents fuel vapors from escaping into the atmosphere. Key components include:

• Fuel tank
• Gas cap
• Charcoal canister
• Purge valve
• EVAP vent solenoid
• Fuel tank pressure sensor
• Hoses and lines connecting components

When the engine is off, fuel vapors are absorbed by the charcoal canister. When the engine is running and reaches optimal conditions, the purge valve opens to allow the vapors to be burned in the engine. The vent solenoid allows fresh air into the canister when the system is not being tested.

Common Causes of P1440

• Faulty purge valve stuck open
• Faulty EVAP canister
• Loose or damaged hoses/connections
• Defective gas cap
• Wiring issues

Diagnosis Steps

1. Visually inspect hoses, wiring, and components for obvious damage.

2. Smoke test the EVAP system to check for leaks. Leaks as small as 0.020" (0.5mm) can trigger the code.

3. Test the purge valve and vent valve for proper operation using a scan tool.

4. If no leaks are found, replace the purge valve/solenoid which is the most likely culprit.

5. Clear codes and retest to verify repair.

Repair Costs

• Purge valve: $50-200 USD / 45-180 EUR + 0.5-1 hour labor
• EVAP canister: $200-600 USD / 180-550 EUR + 1-2 hours labor
• Hoses: $10-50 USD / 9-45 EUR + 0.5-1 hour labor
• Gas cap: $10-30 USD / 9-27 EUR

Total repair costs can range from under $100 to over $1000 (90 to 900 EUR) depending on the specific issue and vehicle.

Preventing EVAP Problems

• Always tighten the gas cap until it clicks.
• Don't top off when refueling.
• Replace cracked, brittle or damaged hoses.
• Address EVAP system leaks promptly.

Related Issues

Other codes that may appear alongside P1440 include:

• P0440 – EVAP System Malfunction
• P0441 – Incorrect Purge Flow
• P0442 – Small EVAP System Leak Detected
• P0446 – EVAP Vent Valve Circuit Malfunction
• P0455 – Large EVAP System Leak Detected

In summary, the P1440 code indicates a stuck open purge valve in the EVAP system. While it's usually safe to drive short distances, it's best to diagnose and repair this issue promptly to minimize emissions and prevent drivability issues. Checking for leaks and faulty valves are the key diagnostic steps.

Frequently Asked Questions about P1440 Engine Code

What does the P1440 code mean?

The P1440 is a manufacturer-specific powertrain code that indicates a small leak detected in the evaporative emission (EVAP) control system, most commonly due to a stuck open purge valve.

Is it safe to drive with a P1440 code?

In most cases, you can continue driving safely with a P1440 code for a short time. However, it's best to diagnose and fix the issue promptly to prevent increased emissions, reduced fuel economy, difficulty starting, or rough idle.

What are the common symptoms of a P1440 code?

You may notice a strong fuel odor, reduced fuel efficiency, rough idle, difficulty starting, or the check engine light illuminated. In some cases, there may be no noticeable symptoms other than the stored code.

What causes a P1440 code?

Common causes include a faulty purge valve stuck open, defective EVAP canister, loose or damaged hoses, bad fuel cap, or wiring issues.

How do you diagnose a P1440 code?

Key diagnostic steps are:

1. Visual inspection of hoses, wiring and components
2. Smoke test to check for leaks
3. Testing purge and vent valves with a scan tool
4. Replacing the purge valve if no leaks found

Can a loose or faulty gas cap cause P1440?

Yes, a loose, damaged or incorrect gas cap can allow fuel vapors to escape, triggering a P1440 code. Always ensure the gas cap is tightened until it clicks.

What is the EVAP system and what does it do?

The EVAP system is designed to contain fuel vapors from the tank and prevent them from escaping into the atmosphere. It routes the vapors to a charcoal canister where they are stored until the engine is running and they can be purged and burned.

Where is the purge valve located?

The purge valve is typically located on or near the intake manifold or charcoal canister. It is electrically controlled by the engine computer.

How do I test the purge valve?

The purge valve can be tested by commanding it open and closed with a scan tool and checking for voltage and clicking sound. You can also visually inspect the valve and test for air flow when disconnected.

What happens if I ignore a P1440 code?

Ignoring a P1440 code can lead to increased evaporative emissions, a failed emissions test, reduced fuel economy, and potentially more expensive repairs if left unaddressed. In rare cases, an excessive fuel vapor leak could be a safety hazard.

How much does it cost to fix a P1440 code?

The cost to repair a P1440 code ranges from under $100 for a gas cap or minor hose to over $600 for an EVAP canister replacement plus labor. Purge valve replacement typically costs $50-$200 for parts plus 0.5-1 hour labor.

Can a smoke test find all EVAP leaks?

A smoke test is an effective way to find most leaks in the EVAP system. However, very small leaks may not be detected and some leaks may only occur under certain conditions like high temperatures or specific fuel tank levels.

What is a charcoal canister and what does it do?

The charcoal canister is a container filled with activated charcoal that absorbs and stores fuel vapors when the engine is off. When the engine is running, the vapors are purged from the canister and burned in the engine.

Can I replace the purge valve myself?

Replacing a purge valve is generally an intermediate DIY job requiring basic tools. However, it can be more difficult on some vehicles, especially if the valve is hard to access. If you are not confident in your repair skills, it's best to have the work done by a professional.

What is the difference between P0440 and P1440 codes?

P0440 is a generic code that indicates a general EVAP system malfunction. P1440 is a manufacturer-specific code used by Nissan and Infiniti that points to a small vapor leak, often due to a stuck open purge valve. The diagnostic steps are similar for both codes.

Can a weak battery cause a P1440 code?

While a weak battery alone is unlikely to cause a P1440 code, low voltage can potentially affect the operation of EVAP system valves and sensors. This could lead to false readings that trigger the code. It's a good idea to check battery condition if the code persists after repairs.

How often should I replace my gas cap?

There is no set interval for gas cap replacement. Inspect it regularly for cracks, brittleness or a worn seal and replace as needed. Avoid over-tightening the cap, as this can damage the seal. If the cap is not holding pressure, the check engine light is on, or you smell fuel, replace the cap.

What are some other common EVAP system codes?

Other common EVAP system trouble codes include:

• P0442 – Small leak detected
• P0455 – Large leak detected
• P0456 – Very small leak detected
• P0441 – Incorrect purge flow
• P0446 – Vent valve circuit malfunction

Will disconnecting the battery erase a P1440 code?

Disconnecting the battery will clear the code from memory, but it will likely reappear if the underlying problem is not fixed. The engine computer will also need to relearn fuel trims and other adaptive values after battery disconnect, so it's best to use a scan tool to clear codes after repairs.

What should I do if the P1440 code comes back after repairs?

If the code returns after purge valve replacement or other repairs, there is likely another problem such as a wiring issue, leaking hose, or faulty gas cap. Double check all connections, clear the code, and retest. Smoke testing is the most reliable way to find hidden EVAP leaks.