DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected. GMC Truck Savana 2000

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2000 🢒 Savana 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

Engine Controls Components
Cell 21: EGR and EVAP Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
VCM Connector End Views
Power Distribution Schematics

Circuit Description

The evaporative system includes the following components:

•	The fuel tank

•	The EVAP vent solenoid

•	The fuel tank pressure sensor

•	The fuel pipes and hoses

•	The vapor lines

•	The fuel cap

•	The evaporative emission canister

•	The purge lines

•	The EVAP purge solenoid

The evaporative leak detection diagnostic strategy is based on applying a vacuum to the EVAP system and monitoring the vacuum decay rate. The VCM monitors vacuum level via the fuel tank vacuum sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid are turned ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge solenoid turns OFF, sealing the system. A leak is detected by monitoring for a decrease in the vacuum level over a given time period. A small leak in the system will cause DTC P0442 to be set.

Conditions for Running the DTC

•	No active MAP sensor DTCs

•	No active TP sensor DTCs

•	No active VSS DTCs

•	No active HO2S DTCs

•	No active ECT sensor DTCs

•	No active IAT sensor DTCs

•	DTC P0125 not active

•	The fuel level is between 12.5 percent and 87 percent.

•	The ECT is between 4°C and 30°C (39°F to 86°F).

•	The IAT is between 4°C and 30°C (39°F to 86°F).

•	The cold start temperature difference (ECT minus IAT) is less than:

1.5°C when the IAT is more than the ECT.

8°C when the ECT is more than the IAT.

•	The BARO is more than 72 kPa.

•	The change in fuel tank vacuum is less than 0.6 inch of H2O, or the change in fuel level is less than 8 percent.

•	The throttle position is less than 75 percent.

•	The vehicle speed is less than 65 MPH.

•	The fuel tank vacuum level remains above a calibrated value for a specified number of seconds.

Conditions for Setting the DTC

The EVAP system is unable to hold a specified vacuum level for a calibrated number of seconds.

Action Taken When the DTC Sets

•	This is a type A DTC that behaves like a B type, in which the VCM illuminates the MIL during the second key cycle.

•	The VCM stores the conditions that were present when the DTC sets as the Freeze Frame and the Fail Records data.

Conditions for Clearing the MIL or DTC

•	The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.

•

A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.

•	Use a scan tool in order to clear the DTCs.

Diagnostic Aids

Important: An accurate indication of fuel level is required for the VCM to properly Pass or Fail this DTC. Always diagnose fuel level sensor DTCs before performing this DTCs diagnostic table. Always check for fuel level sensor DTCs stored in History.

Physically check for the following conditions:

•	A loose, missing, damaged, incorrect, or improperly installed fuel cap.

•	Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings.

•	A cracked or punctured EVAP canister.

•	A damaged or disconnected EVAP purge line, vent hose, or fuel tank vapor line.

•	Incorrectly routed or damaged EVAP system purge and vapor lines

•	A faulty connection at the VCM. Inspect the harness connectors for the following conditions:

-	Backed out terminals

-	Improper mating

-	Broken locks

-	Improperly formed or damaged terminals

-	Faulty terminal to wire connections

•	A damaged harness: Inspect the wiring harness to the EVAP vent solenoid EVAP purge solenoid and the fuel tank pressure sensor for an intermittent, an open, or a short circuit.

•	A kinked, pinched, or plugged vacuum source, EVAP purge, or fuel tank vapor line. Verify that the lines are not restricted.

Refer to Evaporative Emission System Cleaning before beginning repairs.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Inspect the service port. Ensure that the valve core is not damaged. If you suspect the service port of leakage, use the following procedure:

Disconnect the purge line from the evaporative emissions (EVAP) purge solenoid valve.

Connect a hand vacuum pump to the service port by placing the hose and adaptor over the unthreaded end portion of the service port.

Apply vacuum to 5 inches Hg. If the vacuum does not hold, replace the entire purge line that contains the service port.

If the vehicle passes the service bay test, then an intermittent leak had occurred. Check the fuel tank cap for a possible loose or leaking condition that may have caused this DTC to set.

If you cannot run the service bay test, , proceed to step 5. If a fault is not currently present, the diagnostic table steps will return you to step 3.

For the correct set-up and adjustment procedures, refer to the information that is supplied with the EVAP pressure and purge diagnostic cart.

An EVAP pressure sensor that does not correctly respond to pressure or to vacuum will cause this DTC to set.

The EVAP pressure sensor monitors a range from 7.5 inches H2O of pressure to -17.5 inch H2O of vacuum.

Step

Action

Values

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Check for DTCs P0440, P0446, P0452, P0453, P0461, P0462, P0463, and P1441.

Are any other EVAP system DTCs stored in HISTORY?

Go to the DTCs that are set.

Go to Step 3

Inspect the EVAP system for the following conditions:

•	A fuel tank cap

Loose

Incorrect

Defective

Missing

•	EVAP system purge lines that are:

-	Improperly routed

Kinked

Damaged

•	A damaged EVAP system component

•	A loose, missing or damaged service port dust cap or schrader valve. Refer to the Test Descriptions.

Repair the EVAP system, if needed.

Did you make a repair to the EVAP system?

Go to Step 15

Go to Step 4

Important: Before proceeding with the Service Bay Test, the vehicle must meet the following operating criteria:

•	Clear DTC information

•	Battery voltage that is between 10.5 volts and 17.5 volts

•	A fuel level that is between 15 percent and 85 percent

•	Key ON engine temperature is less than 80°C (176°F).

If any of the above conditions are not met, the scan tool will display Test Aborted when you activate the Service Bay Test.

Record the data that was stored when the DTC set and cleared the codes.
Use the scan tool in order to perform the Service Bay Test for the EVAP system.

Does the vehicle pass the Service Bay Test?

Go to the Test Description

Go to Step 5

Turn OFF the ignition.
Remove the EVAP purge line from the EVAP purge solenoid valve.
Connect a hand vacuum pump to the purge connection of the EVAP purge solenoid valve.
Use the hand vacuum pump in order to apply vacuum up to the specified value.

Can you obtain and hold the specified value of vacuum?

12 in Hg

Go to Step 6

Go to Step 10

Reconnect the EVAP purge solenoid valve line.
Disconnect the fuel tank vapor and the EVAP purge line from the EVAP vapor canister.
Plug the canister fitting for the fuel tank vapor line.
Connect a hand vacuum pump to the EVAP purge line canister fitting.
Turn the key ON.
Using a scan tool command the EVAP vent valve ON (CLOSED).
Use the hand vacuum pump in order to apply vacuum up to the specified value.

Can you obtain and hold the specified value of vacuum?

5 in Hg

Go to Step 9

Go to Step 7

Leave system connected as in step 6.
Disconnect the vent line at the EVAP vent valve.
Plug the vent line.
Use the hand vacuum pump in order to apply vacuum up to the specified value.

Can you obtain and hold the specified value of vacuum?

5 in Hg

Go to Step 11

Go to Step 8

Inspect the EVAP vent line from the canister to the EVAP vent valve for leaks.
Replace if needed.

Was the EVAP vent line replaced?

Go to Step 15

Go to Step 12

Important: The following steps require the J 41413 EVAP pressure and purge diagnostic station, and the J 41416 ultrasonic leak detector.

Before you proceed with this diagnosis, always zero the EVAP pressure and vacuum (in H2O) gauges on the EVAP pressure and purge diagnostic station.

Turn OFF the ignition.
Remove the plug and the hand vacuum pump.
Reconnect the EVAP vapor canister purge and the tank vent lines.
Connect the J 41413 EVAP pressure and purge diagnostic station to the EVAP system service port.
Use a scan tool in order to command the EVAP vent valve Closed.

Important: Do Not apply more than 15 inches H2O of pressure to the EVAP system.

Continuously attempt to pressurize the EVAP system by leaving the EVAP pressure and purge diagnostic station control knob in the pressurize position.
Use the J 41416 ultrasonic leak detector in order to locate and repair the EVAP system leak.

Did you find and repair a leak?

Go to Step 15

Go to Step 13

Important: Inspect the EVAP purge solenoid valve and the purge line for carbon contamination. Refer to Diagnostic Aids.

Replace the EVAP purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Is the replacement complete?

Go to Step 15

Replace the EVAP vent valve. Refer to Evaporative Emission Vent Valve Replacement .

Is the replacement complete?

Go to Step 15

Replace the EVAP vapor canister. Refer to Evaporative Emission Canister Replacement .

Is the replacement complete?

Go to Step 15

Relieve all system pressure.
Using the scan tool, use the Purge/Seal function in order to turn the EVAP purge solenoid valve ON to varying vacuum levels with the engine running. Quickly SEAL the system with the scan tool. Leaving the EVAP purge solenoid valve ON for higher percents or longer times will allow a higher amount of vacuum to develop. A maximum of 8.5 inches H2O of vacuum can be applied to the EVAP system using the scan tool.
While the system is sealed, compare the EVAP pressure and purge diagnostic stations vacuum gauge (in H2O) to the vacuum shown on the scan tool from the EVAP fuel tank pressure sensor. Allow a few seconds for the system to stabilize.

Do both values indicate the same amount of vacuum in the EVAP system to within the range specified?

+/ - 2 in H2O

Go to Step 3

Go to Step 14

Replace the EVAP fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement .

Is the replacement complete?

Go to Step 15

Use the scan tool in order to clear the DTCs.
Start the engine.
Allow the engine to idle until the engine reaches the normal operating temperature.
Select DTC and the Specific DTC function.
Enter the DTC number which was set.
Operate the vehicle, with the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

Go to Step 16

Does the scan tool display any additional undiagnosed DTCs?

Go to the applicable DTC table

System OK