P0442 EVAP Leak Monitor Small Leak Detected
NAME OF CODEEVAP System Small Leak
WHEN MONITORED
Immediately after a cold start, with ambient temperature between 40°F and 90°F and coolant temperature within 10°F of ambient temperature.
SET CONDITION
If there is a leak larger than 0.040" and smaller than 0.080" in the evaporative system.
THEORY OF OPERATION
The leak detection assembly incorporates two primary functions: it detects a leak in the evaporative system and seals the evaporative system so the leak detection test can be run.
The primary components within the assembly are a three-port leak detection solenoid that activates both of the functions described above, a pump containing a leak detection pump switch that monitors pump movement, two check valves and a spring diaphragm, and a canister vent valve seat containing a spring-loaded vent seal valve.
When the solenoid is energized, it allows engine vacuum to enter the pump and draw the diaphragm up, thus allowing atmospheric pressure to enter the pump cavity. When the solenoid is deenergized, it vents the engine vacuum thus permitting the spring to drive the diaphragm down, forcing air out of the pump cavity into the vent system. When the solenoid is energized and de-energized, the cycle is repeated, which creates flow in a typical diaphragm pump fashion.
After passing the leak detection phase of the test, system pressure is maintained until the purge system is activated, in effect creating a leak. If the cycle rate increases due to flow of the purge system, the test is passed and the diagnostic test is complete. If not, there is an obstruction in the system.
POSSIBLE CAUSE
- A leak in the evaporative system between 0.040" and 0.080"
- Leak detection pump failure
SAFETY PRECAUTIONS
WARNING: Take the following precautions to prevent personal injury while using this test equipment.
Keep lighted cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases. Keep the test area well-ventilated.
This equipment is designed to be used on the vehicle evaporative system only. Using the equipment in a manner for which it was not designed could be a dangerous procedure.
The vehicle fuel tank must be 1/2 full of gas when conducting this test procedure. Pressurizing a tank containing less than three gallons of gas could resuit in the ignition of fumes, causing an explosion.
Wear protective eye wear that meets the requirements of OSHA and ANSI Z87.1-1968.
When using the battery as a power source, connect the RED (+) battery clip to the positive vehicle battery terminal, and connect the BLACK (-) battery clip to a good ground away from the battery.
If the vehicle being tested is not on a hoist, set the parking brake and block the wheels before starting the test.
EVAPORATIVE SYSTEM PRESSURE TEST
WARNING: Verify the vehicle fuel tank contains at least 3 gallons of fuel.
1 Attach the DRB III to the vehicle.
2 Turn the key on.
3 At: ENGINE SYSTEM TESTS select: LEAK DETECTION PUMP TEST
4 Read instructions and then press ENTER.
5 At: LEAK DETECTION PUMP TEST select #3 HOLD PSI.
6 At the vacuum hose going to LDP attach and apply a continuous vacuum (i.e. 20" Hg).
7 Remove gas cap.
8 Install 6922 on the gas cap and on the vehicle.
9 Attach the supply hose from 6872A to 6922.
10 Attach the power source from the 6872A, clip to battery and ground clip to battery.
11 On the 6872A set the Pressure/Hold valve to open and set the Vent valve to closed.
12 Turn the timer on and watch the gauge.
13 When the gauge pressure reaches 14 in. H20, turn the Pressure/Hold valve to closed.
14 Turn the timer off. Note the time and pressure.
15 Does the pressure drop more than 6 inches (to 8 inches H2O on the gauge) in 2 minutes?
16 If not, the system is OK.
17 If it does, then there is a leak in the system.