2001 Chevrolet/Geo Camaro  

DTC P0440

System Description

The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge valve OPEN and the EVAP vent valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent valves.

Control Module Command

EVAP Canister Purge Valve

EVAP Canister Vent Valve

ON

Open

Closed

OFF

Closed

Open
Conditions for Running the DTC
Conditions For Setting the DTC

The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

Action Taken When the DTC Sets
Conditions for Clearing the MIL/DTC
Diagnostic Aids
Test Description

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

  1. This step is used to verify if a leak is present.

  2. This step verifies proper operation of the fuel tank pressure (FTP) sensor.

  3. This step tests the EVAP canister purge valve for a restriction or blockage.

DTC P0440

Step

Action

Values

Yes

No

Schematic Reference: Evaporative Emissions (EVAP) Hose Routing Diagram

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Does the scan tool indicate DTC P0443 or DTC P0449 are also set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3
  1. Inspect the evaporative emission (EVAP) system for the following conditions:
    • Loose, missing, or damaged service port schrader valve
    • Loose, incorrect, missing, or damaged fuel fill cap
    • A damaged EVAP canister purge valve
  2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Inspect the EVAP system for the following conditions:
    • Disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses
    • A damaged EVAP canister vent valve or EVAP canister

Did you find and correct the condition?

--

Go to Step 18

Go to Step 4

4

Important

The following steps require the J 41413 EVAP Pressure/Purge Diagnostic Station and the J 41415 Fuel Fill Cap Adaptor .

Always zero the EVAP pressure and vacuum in H2O gages on the EVAP pressure diagnostic station before proceeding with diagnosis.

  1. Install the J 41415 .
  2. Connect the J 41413 and the vehicle fuel fill cap to the J 41415 .
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, seal the EVAP system.
  5. With the J 41413 , pressurize the system to the specified value.
  6. Rotate the EVAP pressure/purge diagnostic station rotary switch to the OFF/HOLD position. Monitor the pressure gage for 1 minute.

Did you obtain and hold the specified value?

5 in H2O

Go to Step 5

Go to Step 7

5

Compare the EVAP pressure/purge diagnostic station value to the scan tool fuel tank pressure (FTP) sensor value.

Does EVAP pressure/purge diagnostic station value measure near the scan tool value?

--

Go to Step 6

Go to Step 11

6
  1. Monitor the pressure gage on the J 41413 .
  2. Disconnect the EVAP purge pipe from the EVAP purge valve.

Does the EVAP system pressure decrease?

--

Go to Step 8

Go to Step 9

7
  1. With the J 41413 , continuously pressurize the EVAP system.

    Important

    It may be necessary to partially lower the fuel tank to inspect components located in the upper portion of the tank.

  2. With the J 41416 Ultrasonic Leak Detector, inspect for leaks in the following locations:

Did you locate and repair the system?

--

Go to Step 18

Go to Diagnostic Aids

8

  1. Attach a vacuum gage to the purge pipe port of the EVAP purge valve.
  2. Start and idle the engine.
  3. Command the EVAP purge valve to 50 percent with a scan tool.

Does the vacuum gage show vacuum more than the specified value?

10 in H2O

Go to Intermittent Conditions

Go to Step 12

9
  1. Monitor the pressure gage on EVAP pressure/purge diagnostic station.
  2. Disconnect the EVAP purge pipe from the EVAP canister.

Does the EVAP system pressure decrease?

--

Go to Step 14

Go to Step 10

10
  1. Monitor the pressure gage on EVAP pressure/purge diagnostic station.
  2. Disconnect the EVAP vapor line from the EVAP canister.

Does the EVAP system pressure decrease?

--

Go to Step 17

Go to Step 13

11

Monitor the FTP voltage with a scan tool.

Is the FTP voltage more than the specified value?

4.3 V

Go to DTC P0453

Go to Step 15

12
  1. Inspect the vacuum source to the EVAP purge valve for the following conditions:
    • Blockage
    • Cuts
    • Disconnects
  2. Repair as necessary.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

13

Repair for a pinched or obstructed EVAP vapor pipe.

Did you complete the repair?

--

Go to Step 18

--

14

Repair the restriction in the EVAP purge pipe. Refer to Evaporative Emission (EVAP) System Cleaning .

Did you complete the repair?

--

Go to Step 18

--

15

Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 18

--

16

Replace the EVAP purge valve. Refer to Evaporative Emission (EVAP) Canister Purge Valve Replacement .

Did you complete the repair?

--

Go to Step 18

--

17

Replace the EVAP canister. Refer to Evaporative Emission (EVAP) Canister Replacement .

Did you complete the repair?

--

Go to Step 18

--

18
  1. Turn ON the ignition, with the engine OFF.
  2. Command the EVAP vent valve ON with a scan tool.

    Important

    Do not exceed the specified value in the step. Exceeding the specified value may produce incorrect test results.

  3. Pressurize the EVAP system to the specified value with the J 41413 .
  4. Place the control knob on the J 41413 to the OFF/HOLD position.
  5. Monitor the EVAP system pressure on the J 41413 for 5 minutes.

Does the scan tool indicate that the Service Bay Test passed?

5 in H2O

Go to Step 19

Go to Step 7

19
  1. Monitor the pressure gage on the J 41413 .
  2. Command the EVAP purge valve to 50 percent.

Does the EVAP system pressure decrease?

--

Go to Step 20

Go to Step 9

20

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK