Evaporative Emission Control System Diagnosis. Oldsmobile LSS 1998

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1998 🢒 LSS 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Evaporative Emission Control System Diagnosis

Engine Controls Components
Cell 20: EGR Valve, EVAP System
OBD II Symbol Description Notice

Conditions for Setting the DTC

•	No TP sensor, ODM, IAT sensor, or MAP sensor DTCs set.

•	The DTC P0442 diagnostic test has passed.

•	A continuous open purge flow condition is detected during the diagnostic test (fuel tank pressure decreases to less than -11 in. H2O).

Action Taken When the DTC Sets

•	The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed.

•	The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

Important: Although these diagnostics are considered type A, they act like type B diagnostics under certain conditions. Whenever the EVAP diagnostics report that the system has passed, or if the battery has been disconnected, the diagnostic must fail during two consecutive cold start trips before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.

Conditions for Clearing the MIL/DTC

•	The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.

•	The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC can be cleared by using the scan tool.

Diagnostic Aids

Check for the following conditions:

•	Poor connection at the PCM.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

•	Damaged harness.

Inspect the wiring harness for damage.

•

If the harness appears to be OK, connect the
Object Number: 20803 Size: SH


(1)	Main Valve
(2)	Evaporative Emission System Purge/Presure Diagnostic Station J 41413
(3)	Nitrogen Cylinder
(4)	Black Connecting Hose
(5)	Threaded Fitting
(6)	Gauge Set

•	Incorrect vacuum line routing.

Verify that the source vacuum line routing to the EVAP purge valve is correct and that the EVAP purge and source vacuum lines to the EVAP purge valve are not switched.

•	Malfunctioning or damaged canister.

A malfunctioning canister may intermittenly allow charcoal into the EVAP purge valve, EVAP vacuum switch, and associated lines causing a DTC to be set. Use the following procedure to check for a carbon release condition:

1.	Turn OFF the ignition switch.

2.	Remove the EVAP purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement

3.	Lightly tap the EVAP purge valve and (if applicable) the vacuum switch on a clean work area looking for carbon particles exiting either of the vacuum ports.

4.	If no carbon release is evident, reinstall the components and continue with the DTC P1441 table. If carbon is being released from either component, continue with this service procedure.

5.	Remove the EVAP canister from the vehicle.

Ensure that the main cylinder valve is turned off on the
Object Number: 20803 Size: SH


(1)	Main Valve
(2)	Evaporative Emission System Purge/Presure Diagnostic Station J 41413
(3)	Nitrogen Cylinder
(4)	Black Connecting Hose
(5)	Threaded Fitting
(6)	Gauge Set

7.	Disconnect the black hose that connects the nitrogen cylinder to the EVAP purge/pressure diagnostic station at the pressure regulator by unscrewing the knurled nut on the regulator. No tools are required to remove the black hose from the regulator.

8.	Using a section of vacuum line, connect one end over the open threaded fitting of the EVAP purge/pressure diagnostic station pressure regulator.

9.	Connect the remaining end to the EVAP purge valve end of the EVAP purge line at the vehicle and turn on the main nitrogen cylinder valve. Continue to blow any debris from the purge line for 15 seconds.

10.	Return the EVAP Pressure/Purge Diagnostic Station to its original condition by re-installing the black hose that was disconnected in step 7.

11.	Replace the following components:

-	The EVAP purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement

-	The EVAP canister. Refer to Evaporative Emission Canister Replacement

12.	Proceed with the the DTC P1441 diagnostic table.

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

Test Description

Numbers below refer to the step numbers on the Diagnostic Table.

The PCM will command the EVAP purge and EVAP canister vent valves closed with the scan tool Seal System EVAP output control function activated. Fuel tank pressure should not decrease under this condition.

The PCM commands the EVAP purge valve OFF (open) and the EVAP canister vent valve ON (closed) with the scan tool System Perf. EVAP output control function activated. Engine vacuum should cause fuel tank pressure to decrease when System Perf. is activated.

Enhanced Evaporative Emission System Check

Step

Action

Values

Yes

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Important: Visually/physically inspect for the following conditions:

•	Vacuum or purge lines disconnected. Refer to Emission Hose Routing Diagram .

•	Loose or missing fuel cap.

Turn OFF the ignition switch.
Remove the fuel cap.
Turn ON the ignition switch.
Observe Fuel Tank Pressure on the scan tool.

Is Fuel Tank Pressure at the specified value?

0 in. H2O

Go to Step 3

Go to Fuel Tank Pressure Sensor Diagnosis

Important:: Before continuing with diagnosis, zero the EVAP Pressure and Vacuum (inches of H2O) gauges on the
Object Number: 20803 Size: SH


(1)	Main Valve
(2)	Evaporative Emission System Purge/Presure Diagnostic Station J 41413
(3)	Nitrogen Cylinder
(4)	Black Connecting Hose
(5)	Threaded Fitting
(6)	Gauge Set

EVAP pressure/purge diagnostic station (refer to tool operating instructions).

Replace the fuel cap.
Using the scan tool, command the EVAP canister vent valve ON (Closed).
Connect the EVAP pressure/purge diagnostic station to the EVAP service port.
Pressurize the EVAP system to the specified value using the

(1) Main Valve

(2) Evaporative Emission System Purge/Presure Diagnostic Station J 41413

(3) Nitrogen Cylinder

(4) Black Connecting Hose

(5) Threaded Fitting

(6) Gauge Set

EVAP pressure/purge diagnostic station (monitor pressure using gauge on the EVAP pressure/purge diagnostic station).
Observe Fuel Tank Pressure on the scan tool.

Is Fuel Tank Pressure at the specified value?

5 in. H2O

Go to Step 4

Go to Fuel Tank Pressure Sensor Diagnosis

Monitor the EVAP Pressure gauge on the EVAP pressure/purge diagnostic station while commanding the EVAP canister vent valve OFF (Open).

Does EVAP Pressure decrease to the specified value within 5 seconds?

0 in. H2O

Go to Step 5

Go to DTC P1665 Evaporative Emission (EVAP) Vent Solenoid Control Circuit

Start the engine.
Remove the fuel cap.
Using the scan tool output tests function, select Seal System and activate.
Replace the fuel cap.
Switch the rotary switch on the EVAP pressure/purge diagnostic station to PURGE.
Run the engine at idle while monitoring the Vacuum (inches of H2O) gauge on the EVAP pressure/purge diagnostic station.

Is vacuum increasing to a value greater than the specified value?

0 in. H2O

Go to DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge

Go to Step 6

Using the scan tool output tests function, select System Perf. and activate.
Switch the rotary switch on the EVAP pressure/purge diagnostic station to PURGE.
Run the engine at 2500 RPM while monitoring the Vacuum (in. of H2O) gauge on the EVAP pressure/purge diagnostic station for at least 10 seconds.

Did vacuum increase to a value greater than the specified value?

-5 in H2O

System OK

Go to DTC P0440 Evaporative Emission (EVAP) System