Question about 2002 Ford Taurus
I have a 2002 Ford Taurus, and an engine sign showed up. However, I pulled out the code which is P0442.
what is the problem, how much would that cost me and when do I need to fix it, can I wait for the next week, or its something that needs to take care of ASAP.
This is intended to provide basic information about the P0442 fault code, what can and cannot cause it to occur, but also includes technical information for a better understanding of this code as well as the diagnostic procedures involved. This information is from our emissions expert and we suggest taking this to the shop if they are having problems diagnosing this code.
OBD II Fault Code:
Fault Code Definition:
Evaporative System Malfunction, small leak
Common Problems that Trigger the P0442 code:
HC’S –Hydrocarbons -> unburned droplets of raw fuel that smell, effect breathing and color the sky
The evaporative control (EVAP) system captures any raw fuel evaporating from the fuel storage system (e.g. the fuel tank, the filler neck, and fuel cap). Under precise operating conditions dictated by engine temperature, speed, and load, the EVAP system stores and purges these captured fuel vapors back into the combustion process.
The Evaporative Control System is designed to not only capture, store and purge any raw fuel vapors that leak from any areas of the Fuel Storage System but also to run a series of self-tests that confirm or deny the Operational and Vapor Holding ability of the System. This is an important task because at least 20% of the Vehicle produced Air Pollution originates from malfunctioning Vehicle Fuel Storage Systems. There are many ways for vehicles to 'leak test' the Evaporative System, but most perform the leak test either when the vehicle is sitting, say over night, or shortly after initial start up after the vehicle has been sitting over night. The Evaporative Systems operational performance is also tracked by the Power Train Computer by reading the change in the Oxygen Sensor voltages and Short Term Fuel Trim when ever the stored Vapors are released or 'purged' back into the combustion process. These values should indicate that fuel is being added to the system and that the over all mixture is getting richer. The purging process occurs when the vehicle is under acceleration, which is when most vehicles require additional fuel.
P0442 Diagnostic Theory for Shops and Technician
The Code P0442 indicates that there is a small leak in the Evaporative System, but this is somewhat misleading. What the code really indicates is that the Evaporative System will not hold a specified level of vacuum for a specified amount of time when it performs its leak test. Let's go over a little about how the Evaporative Leak Test is performed by the Power Train Computer. When the leak test is performed, on most vehicles, the vehicle must have been sitting for at least 4-8 hours in order for the Engine Temperature and Air Temperature to be identical. This is to provide a base line for the test because gasoline and diesel fuel are volatile fluids that expand and vaporize easily with warm temperatures. When the Leak Test initiates, the Vapor Canister Vent Valve is closed to prevent any fresh air from entering the Evaporative System. Then the Purge Valve is opened which allows the engine to create a vacuum in the sealed off Evaporative System. After a specified time interval, which is usually about 10 seconds, the Purge Valve is shut off and the vacuum level in the system is measured with the Fuel Tank Pressure Sensor. Then a count down initiates which measures the rate at which the vacuum decays in the system. If the vacuum decays faster than the specified rate on 2 successive tests, then the Power Train Computer will fail the Evaporative System for a small leak and set the code P0442. Most modern Evaporative Systems will fail the leak test and set a code P0442 with a pin sized hole anywhere in the Evaporative System, which amounts to 0.020 of an inch or ½ of a millimeter ( 0.040 ).
Posted on Oct 06, 2009
What does that mean?
This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine
Symptoms You likely won't notice any drivability problems.
Causes A code P0442 most likely means one or more of the following has happened:
Hope this helps you.
Posted on Oct 06, 2009
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Posted on Jan 02, 2017
SOURCE: I have a 2002 Ford
P0442 code relating to the EVAP (Evaporative Emission System).a small emissions leak. also check the gas cap .Try cleaning the seals first and then try putting a little vaseline on the seals before getting a new gas cap.
Code P0442-Evaporative emission control system. Canister Purge system failed the monitor test indicating a large leak (over 0.040”). Enabling conditions: Engine running after a 6 to 8 hour engine off period called a cold soak. The test runs when engine load is between 15 to 45% and inlet air temperature between 40 and 130°F. Blocking Action: This code can block the following monitors: Fuel Control, O2 monitor, Catalyst Monitor, misfire monitor. Testing: Check the purge hoses for leaks, leaking vapor management valve or loose gas cap.
This simply indicates that there was no flow from the evap system when the purge valve was energized. This could be cause of a few different reasons. First, check for leaks by visually looking at all evap lines for cranks rips or any tears. Basically, anywhere that fuel vapors can escape.
----------- Here is the test that will smoke the system for leaks with a smoke machine.
Evaporative Emission System Leak Test
CAUTION: The evaporative emission system must not be pressurized to more than 3.48 kPa (14 inches H2O)or damage to the evaporative emission system may occur.
Posted on Oct 15, 2009
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