P1440 Code: Causes and Fixes of Evaporative Emission System Leaks

Engine warning lights are often accompanied by vibrations, weird noises, or smells that can help track the root cause of the underlying problem. But sometimes, that panic-inducing light illuminates with no indication of what’s up. That is mostly the case with evaporative emission system leaks.

If your car computer detects small leaks on the evaporative emission system, it will throw a P1440 code. What is a P1440 fault code, you may be asking? We’ll explain that as we progress along.

But what’s more important to know now is that the P1440 error code is related to leaks on the EVAP system. If there’s an EVAP leak, your car won’t catch fire, and you may not have any drivability issues.

However, it is also not a problem you should ignore for an extended period. This article will outline the causes, symptoms, and how to diagnose and fix the culprit.

p1440 code nissan maxima

What does error code P1440 mean?

The Evaporative emission system, also known as the EVAP system, prevents fuel vapor from escaping into the atmosphere. Instead, the EVAP system sends the fuel vapor back to the engine for a re-burn via the intake manifold.

This is essential because fuel vapors contain several hydrocarbons. The hydrocarbons form smog when it comes in contact with sunlight and air. No doubt, gasoline evaporates quickly. Therefore, if the fuel system is opened to the atmosphere, the car will pollute round the clock without running.

Auto manufacturers install EVAP system components to ensure the fuel vapor is returned back to the engine without causing pollution to the atmosphere. If the powertrain control module (PCM) detects a small leak in the EVAP system, it will throw a P1440 error code.

What is the symptom of error code P1440?

If the car computer detects a P1440 code on Honda Civic or any car model, it will project some signs to notify the driver of an underlying issue in the EVAP system. Undoubtedly, the signs of a P1440 code on ford and a P1440 code on Nissan may differ.

Although there are some symptoms, you will see across all car models, others will occasionally come up, depending on your car model. In any case, the most prominent signs of a logged P1440 error code are check engine light, failed emission inspection, and gas smell. Let’s discuss these signs in detail.

Check engine light

The ECM will project a check engine soon light or engine warning light once there’s a leak on the EVAP system. If the car computer throws a P1440 error code, it will also project the check engine light to notify the driver of an imminent issue with a system component.

The powertrain control module throws the P1440 code on Nissan Altima or your respective car model in accordance with the signal it receives from the EVAP systems.

In any case, it’s important to note that several factors can cause the car computer to project the check engine light on the dashboard. Therefore, do not conclude there is a leak in the EVAP system without a proper diagnosis.

Gas odor

One of the common signs of a P1440 error code is gas smell. This gas odor mainly emits from faulty engine components in the vehicle, but the primary cause is a broken EVAP canister. A damaged or broken EVAP canister will emit a strong gas odor.

Bad gas mileage

Poor gas mileage shows a vehicle is operating below the manufacturer’s predetermined efficiency. It also indicates there’s either a gas leak or high gas consumption. It’s important to note that several parameters can cause bad gas mileage, including evaporative emission system leaks.

A P1440 case means the fuel vapor that is supposed to return to the combustion chamber for a re-burn has evaporated into the atmosphere. When this happens, you will lose some gas during combustion. This means more money for gas refills and more visits to gas stations.

Failed emission test

Undoubtedly, all vehicles with check engine lights on the dashboard will fail emission inspection. And the car computer always projects the engine warning light whenever it detects small or big leaks on the EVAP system.

p1440 code honda civic hybrid

What Causes error code P1440

A P1440 diagnostic trouble code and other related codes like P1441 code, P1442, and P1443 codes are caused by EVAP system-related issues. Here are the probable causes you should check when tracking the root cause.

  • Faulty EVAP pressure sensor
  • Damaged EVAP canister vent control circuit
  • Broken EVAP system tubing or rubber hose
  • EVAP canister is saturated with water
  • Bad absolute pressure sensor
  • Gas cap not properly closed
  • The defective gas tank relief valve
  • Leaking fuel tank or exhaust canister
  • Using a wrong fuel tank cover

How serious is error code P1440?

A P1440 error code is a common issue because it will not keep you stranded in the middle of nowhere. Additionally, you will unlikely experience drivability and other severe challenges. However, this doesn’t mean you should ignore the issue for an extended period. It will cause bad gas mileage, check engine light, and lead to a failed emission inspection.

How to diagnose

You need a detailed guide if you want to diagnose and fix the P1440 engine code at home without wrongly throwing money at parts. Luckily, this simplified guide will walk you through diagnosing and fixing the EVAP system leak issues.

In addition, the diagnosis is a moderate case that even amateur mechanics and DIYers can do with the right guide.

Items and Tools Needed

Step 1: Scan the vehicle

Find the vehicle diagnostic port beneath the steering wheel. Run the scan check and read all registered fault codes. If other codes exist, track and fix the culprit before heading to the next step.

Step 2: Examine the gas cap

Check if the gas cap is tightened correctly. If it’s not, verify if it is damaged, blocked, or loose. Then, fix the cause and see if that resolves the problem. Sometimes, it could be that you didn’t tighten the gas cap properly after refueling at a self-service gas station.

Step 3: Inspect the EVAP canister and Fuel tank

A leaking EVAP canister is one of the most common causes of a P1440 code on Ford Escape and other car models. Check the EVAP canister and the fuel tank and verify if there’s a leak in any of these components. If you notice a leak, track the exact spot and repair it.

The vapor or charcoal canister is typically located underneath the vehicle, besides the gas tank. It is mainly covered with a plastic cover.

Step 4: Inspect the EVAP canister purge valve

Locate and inspect the EVAP canister control purge valve in the engine bay. It is connected to a hose coming from the canister to the intake. In most vehicles, it is located close to the fuel pump. Make necessary adjustments if you notice any damage to the purge valve or the piping.

Step 5: Examine the EVAP pressure sensor

Locate and examine the EVAP pressure sensor. Ensure it is working according to the manufacturer’s specifications.

Common P1440 diagnosis mistakes

The most common diagnostic mistake among mechanics and DIYers when diagnosing a P1440 error code is not checking the gas cap before anything else. As common as it may sound, an improper tightened or loose gas cover can be the root cause of the P1440 code on Ford focus or your respective car model.

Always start diagnosis with the minor probable cause before navigating to expensive and unlikely causes.

How do you fix P1440?

As reiterated above, several parameters can cause a P1440 code on VW and other car modes. Therefore, you may need several probable solutions to fix the problem. Here are the possible fixes.

  • Replace EVAP purge valve or piping
  • Replace EVAP charcoal canister
  • Fix leaking gas tank
  • Replace a damaged gas cover
  • Tighten a loose gas cap
  • Replace lousy EVAP sensor.

Approx. Repair Cost

It is almost impossible to estimate a P1440 repair cost without a proper diagnosis. If you’re not a DIYer or decide to take your car to a repair shop, the service technician will start with an hour of diagnosis. Most mechanics charge $75 to $150 per hour, depending on your region.

If you have the service technician fix the problem, he’ll add the diagnostic cost to the repair cost. In a P1440 case, you’ll have to fix one or more of the following. The prices below include the repair cost and replacement part price.

  • Tighten or replace gas cap $30 to $75
  • Replace charcoal canister $250 to $600
  • Canister purge valve replacement $75to $200
  • Gas tank repair or replacement $150 to $1000.

Final Words

There’s no doubt that several factors can cause the car computer to throw a P1440 code. But all the probable causes are EVAP system related are easy to track and fix.

This article has provided the symptoms, causes, diagnostic mistakes, and how to track and fix the culprit. Follow the above guides to fix the issues and get back on the road with confidence on the wheel. However, if you do not trust your guts, seek professional help.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

Recent Posts