p0440 — OBD-II Trouble Code

1 Июн 2015 | Author: | No comments yet »
Toyota Corolla II

p0440 — OBD-II Code

Auto Systems and

Evaporative System Malfunction, Leak

Our emissions expert has put the following information about the fault code. We have included diagnostic procedures you can to your repair shop if the is having difficulty analyzing the

OBD II Fault Code

OBD II P0440

Code Definition

Check Light will illuminate

In cases, there are no adverse noticed by the driver

In some there may be a noticeable fuel caused by the release of fuel

Common Problems That the P0440 Code

Missing cap

Defective or damaged fuel cap

or damaged Fuel Tank Neck

Torn or punctured system hose(s)

Defective Tank Sending Unit or seal

Split or damaged Canister

Defective Evaporative Valve and/or Evaporative Valve

Defective or damaged fuel

Common Misdiagnoses

Fuel cap

Purge Valve

Evaporative Valve

Polluting Gases

HCs (Hydrocarbons): Unburned droplets of raw that smell, affect and contribute to smog

The Basics

The control (EVAP) system any raw fuel evaporating from the storage system (e.g. the tank, filler neck, and cap). Under precise conditionsdictated by engine temperature, and loadthe EVAP system and purges these captured vapors back into the process.

Want to Learn

The EVAP system is designed not to capture, store, and purge any raw vapors that leak areas in the Fuel Storage but also to run a series of self-tests confirm or deny the operational and holding ability of the system. is an important task because at 20 percent of vehicle-produced air pollution from malfunctioning Vehicle Storage systems.

There are many ways to test the EVAP system, but perform the leak test the vehicle is sitting (like night) or during the initial after the vehicle has been over night. The EVAP operational performance is also by the Powertrain Computer by reading the in the oxygen sensor voltages and term fuel trim the stored vapors are released or back into the combustion These values should that fuel is being to the system and that the overall is getting richer. The purging occurs when the vehicle is acceleration, which is when vehicles require additional

P0440 Diagnostic Theory for and Technicians

The P0440 code that there is a large in the EVAP system, but this is misleading. What the code indicates is that the EVAP will not create a significant when it performs its leak as monitored by the Fuel Tank Sensor .

Here is how the evaporative leak is performed by the Powertrain Computer:

the leak test is performed, the must have been for at least four to eight so that the engine temperature and air temperature are identical. There also be between 15 and 85 percent in the tankthis is to provide a baseline for the since gasoline and diesel are fluids that expand and easily with warm

When the leak test the Vapor Canister Vent is closed to prevent any fresh air entering the EVAP system.

The Valve is opened, which the engine to create a vacuum in the system.

After a specified intervalusually about ten secondsthe Valve is shut off and the vacuum in the system is measured by the Fuel Pressure Sensor.

Finally, a countdown initiates, measures the rate at which the decays in the system. If the vacuum much faster than the rate or if no amount of vacuum is on two consecutive tests, then the Computer will fail the system for a gross leak and the P0440 code.

Common for the Evaporative System

Retrieve the and write down the freeze information to be used as a baseline to and verify any repair.

Perform a and close visual inspection of all hoses and components in the EVAP for any signs of damage or degradation.

a scan tool, pay very attention to the Fuel Tank readings. Does the Fuel Pressure Sensor work If it doesn’t, the system will that no pressure or vacuum is created when the EVAP is performed when, in fact, is a pressure/vacuum being created Fuel Tank Pressure is unable to read. The Fuel Pressure Sensor is the primary sensor that the Powertrain relies on for the leak test each time the EVAP is run.

Inspect and test the fuel cap to how well it fits onto the Tank Filler Neck. sure the Fuel Cap Seal dry or cracked. If the cap will not seal or vacuum/pressure, then it can trigger the code.

Verify that the Valve and the Vent Valve properly and hold vacuum for a amount of timeat least to sixty seconds. If either one of valves function improperly, the will not develop and/or the proper amount of vacuum.

If all the seem to function properly, perform another smoke of the entire EVAP system. will usually root out any that are hidden behind under components of the vehicle. Pay attention to the Fuel Tank Neck, the Carbon Canister, and the Tank itself, especially the Fuel Pump and Fuel Sending unit are located and Occasionally when a Fuel is replaced, the seal isn’t or properly installed. This can small leaks in the system. You have to remove the rear to further inspect and pinpoint the of a Fuel Tank leak.

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