DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected. Cadillac Seville 1998

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 1998 🢒 Seville 🢒 Engine 🢒 Engine Controls - 4.0L and 4.6L 🢒 DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

Engine Controls Components
Cell 20: EVAP and EGR Valve
OBD II Symbol Description Notice
ESD Notice

Circuit Description

The PCM tests the EVAP system for the following conditions:

•	Large and small leaks (P0440 and P0442)

•	Excess vacuum (P0446)

•	Purge flow during non-commanded conditions (P1441)

•	Fuel Pressure sensor and Fuel Level sensor faults (P0452, P0453, P0461, P0462 and P0463)

•	EVAP Purge and Vent Valve faults (P1645 and P1646)

The PCM monitors the amount of vacuum in the EVAP system by monitoring the Fuel Tank Pressure sensor. For this DTC the PCM turns ON both the EVAP Purge Valve and the EVAP Vent Valve when the Conditions for Running the DTC are met. This applies an engine vacuum to a closed EVAP system. The PCM turns OFF the EVAP Purge Valve when the system reaches the correct amount of vacuum. With the EVAP Purge Valve OFF and with the EVAP Vent Valve ON, the EVAP system should HOLD the vacuum in the EVAP system. This test will indicate a small leak if the EVAP system fails to hold enough vacuum for a specific length of time. This DTC will set after two consecutive failures of the above test.

Conditions for Running the DTC

•	DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0141, P0151, P0152, P0153, P0154, P0452, P0453, P0503, P1111, P1112, P1114, P1115, P1133 or P1153 are not set.

•	Battery voltage is between 10.5 and 17.5 volts.

•	Barometric pressure is more than 71.78 kPa.

•	Fuel level is between 10% and 89.8% of full capacity for at least 3.2 seconds continuously. The time limit is required because fuel sloshing within the tank may cause the fuel level indication to vary outside the fuel level limits.

•	Coolant temperature is between 2°C and 32.7°C.

•	Intake air temperature is between 2°C and 32.7°C

•	Start up coolant and intake air temperature are within 14.2°C of each other.

•	Vehicle speed less than 82 MPH.

Conditions for Setting the DTC

The vacuum in the EVAP system decays (leaks) at too fast a rate.

Important: This DTC does NOT report a first failed test. A first fail of this DTC will have a scan tool status as Not Run. Use the scan tool data display parameter of EVAP TEST RESULT to determine if this DTC has failed or passed for THIS ignition cycle.

Action Taken When the DTC Sets

•	The PCM will illuminate the Malfunction Indicator Lamp (MIL) after two consecutive drive trips that the diagnostic runs and fails.

•	The PCM will record operating conditions at the time the DTC sets. This information will be stored in the Freeze Frame and Failure Records.

•	A first failure of this DTC will store in Last Test Failed but not History.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

•	A Last Test Failed DTC will clear when the diagnostic runs and does not fail.

•	A History DTC will clear after forty consecutive warm-up cycles with no failures of any diagnostic test.

•	Use a scan tool to clear DTCs.

•	Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

Diagnostic Aids

Important: An accurate indication of fuel level is required for the PCM 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 as History.

Perform a physical inspection of the EVAP system. Check for the following conditions:

•	A loose, missing, defective, or incorrect fuel tank cap

•	Incorrectly routed or defective EVAP system vacuum and vapor lines

•	A malfunctioning or damaged EVAP vapor canister

Check for charcoal release from the EVAP vapor canister. Refer to the EVAP System Cleaning procedure.

The vacuum and pressure in the EVAP system is measured in inches of water (H2O). Most gauges measure vacuum in inches of mercury (Hg) and pressure in pounds per square inch (psi). The following shows how the values compare:

in H2O	in Hg	psi
1in H2O	0.07 in Hg	0.0361 psi
5 in H2O	0.36 in Hg	0.180 psi
10 in H2O	0.73 in Hg	0.361 psi
15 in H2O	1.10 in Hg	0.541 psi

Test Description

Inspect the service port. Make sure that the dust cap and valve core is not loose or damaged (the valve core may have left hand threads). If service port leakage is suspected use the following procedure:

Disconnect the purge line from the EVAP Purge solenoid valve.

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

Apply vacuum to 5 in. Hg. If the vacuum does not hold replace the service port (may require line replacement).

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 the Service Bay Test can not be run, proceed to Step 5. If a fault is not currently present the diagnostic table steps will return you to Step 3.

Refer to the information supplied with the EVAP pressure/purge diagnostic cart on proper setup and adjustment procedures.

If a leak was not found in Step 9 and the vehicle is equipped with On Board Refueling Vapor Recovery (Aurora or Seville) connect the EVAP pressure/purge Diagnostic station with the fuel cap adaptor (J 41415-40) to the fuel tank filler neck and repeat Step 9. These ORVR vehicles are equipped with a check valve at the base of the filler tube which may not allow pressure from the EVAP service port to be applied to the filler tube and the fuel cap.

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

The EVAP Pressure Sensor monitors a range from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).

Step

Action

Value(s)

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 DTC's P0440, P0446, P0452, P0453, P0461, P0462, P0463, P1441, P1645 and P1646.

Are any of the above EVAP system DTC's stored in HISTORY?

Go to DTC's that are set.

Go to Step 3

Inspect the EVAP system for the following conditions:

•	A loose, incorrect, or defective fuel tank cap.

•	Improperly routed, or damaged EVAP system purge lines.

•	A damaged EVAP system component.

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

Repair if necessary:

Was a repair made to the EVAP system?

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 4

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

•	Battery voltage between 10.5 and 15 volts.

•	Fuel level between 7 and 63 Litres.

•	Key ON engine temperature between 3.5°C and 35°C.

Perform the Service Bay Test for the EVAP system.

Does the vehicle pass the Service Bay Test?

Fault not present. Refer to Test Descriptions

Go to Step 5

Turn the ignition OFF.
Remove the vacuum source connection from the EVAP Purge Solenoid Valve.
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.
Using the hand vacuum pump apply vacuum up to the specified value.

Can the specified value of vacuum be obtained and held?

12 in. Hg.

Go to Step 6

Go to Step 10

Reconnect the EVAP Purge Solenoid Valve lines.
Disconnect the fuel tank vapor and the EVAP purge line from the EVAP vapor canister.
Plug the canister fitting of the fuel tank vapor line.
Connect a hand vacuum pump to the EVAP Purge line canister fitting.
With the ignition ON, command the EVAP Vent Valve ON (closed) with a scan tool.
Using the hand vacuum pump apply vacuum up to the specified value.

Can the specified value of vacuum be obtained and held?

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.
Using the hand vacuum pump apply vacuum up to the specified value.

Can the specified value of vacuum be obtained and held?

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 Powertrain Control Module Diagnosis for Verify Repair

Go to Step 12

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

Always zero the EVAP Pressure and Vacuum (in. H2O) gauges on the EVAP pressure/purge diagnostic station before proceding with diagnosis.

Turn the ignition OFF.
Remove the plug and the hand vacuum pump.
Reconnect the EVAP vapor canister purge and tank vent lines.
Connect the EVAP pressure/purge diagnostic station J 41413 to the EVAP system service port.
Using a scan tool command the EVAP Vent Valve ON (closed).
Continously attempt to pressurize the EVAP system by leaving the EVAP pressure/purge diagnostic station control knob in the pressurize position.
Using the ultrasonic leak detector J 41416 locate and repair EVAP system leak.

Was a leak found and repaired?

Go to Powertrain Control Module Diagnosis for Verify Repair

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. Go to Evaporative Emission Canister Purge Solenoid Valve Replacement for replacement procedures.

Is the replacement complete?

Go to Powertrain Control Module Diagnosis for Verify Repair

Replace the EVAP Vent Valve. Go to Evaporative Emission Vent Valve Replacement for replacement procedures.

Is the replacement complete?

Go to Powertrain Control Module Diagnosis for Verify Repair

Replace the EVAP Vapor Canister. Go to Evaporative Emission Canister Replacement for replacement procedures.

Is the replacement complete?

Go to Powertrain Control Module Diagnosis for Verify Repair

Relieve all system pressure.
Using the scan tool, use the Purge/Seal function to turn the EVAP Purge Solenoid Valve ON to varying vacuum levels with the engine running and 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 14 in. H2O of vacuum can be applied to the EVAP system using the scan tool.
While the system is sealed compare the EVAP pressure/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?

+ or - 2 in. H2O

Go to Step 3

Go to Step 14

Replace the EVAP Fuel Tank Pressure Sensor. Go to Fuel Tank Pressure Sensor Replacement for replacement procedures.

Is the replacement complete?

Go to Powertrain Control Module Diagnosis for Verify Repair