GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Impala 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 DTC P0440
Table 1: 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
    • DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106, P1107, P1112, P1114, P1115, P1121, or P1122 are not set.
    • The ignition voltage is between 10-18 volts.
    • The barometric pressure (BARO) is more than 75 kPa.
    • The fuel level is between 15-85 percent.
    • The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
    • The intake air temperature (IAT) is between 4-30°C (39-86°F).
    • The start up ECT and IAT are within 9°C (16°F).
    • The vehicle speed sensor (VSS) is less than 121 km/h (75 mph).

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
    • The control module will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test ran and failed.
    • The control module will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC
    • The control module will turn the MIL OFF during the first trip in which the diagnostic has been run and passed.
    • A last test failed (current DTC) clears when the control module turns OFF the MIL.
    • The history DTC will clear after the control module runs and passes 40 consecutive warm up cycles with no failure.
    • The DTC can be cleared by using a scan tool.

Diagnostic Aids
    •  Use theJ 41413 EVAP Pressure and Purge Station in order to pressurize the EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with the J 41416 Ultrasonic Leak Detector.
    • A temporary blockage in the EVAP canister purge valve, purge pipe or EVAP canister could cause an intermittent condition.
    •  Reviewing the Failure 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.

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

    2.

  2. This step verifies proper operation of the FTP sensor.

    3.

  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 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:
    2. • 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:
    4. • 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: Always zero the EVAP pressure and vacuum (in. H2O) gages on the EVAP Pressure and Purge Station before proceeding with diagnosis.

  1. Install the J 41415-40 Fuel Tank Cap Adaptor.
  2. Connect the J 41413 EVAP Pressure and Purge Station and the vehicle fuel fill cap to the J 41415-40 .
  3. Turn ON the ignition, with the engine OFF.
  4. Seal the EVAP system with the scan tool.
  5. Pressurize the system to the specified value with the J 41413 .
  6. Rotate the J 41413 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 J 41413 value to the scan tool fuel tank pressure (FTP) sensor value.

Does J 41413 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. Continuously pressurize the EVAP system with the J 41413 .

    2. Important: You may need to partially lower the fuel tank to inspect components located in the upper portion of the tank.

  2. Inspect for leaks in the following locations with the J 41416 Ultrasonic Leak Detector:
    3. • The EVAP system purge pipe--Refer to Evaporative Emission Hoses/Pipes Replacement - Chassis/Canister .
    • The EVAP vent hose/pipe.
    • The fuel fill pipe/hose and fuel fill cap--Refer to Filler Tube Replacement .
    • The EVAP canister--Refer to Evaporative Emission Canister Replacement .
    • The EVAP canister vent valve--Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement .
    • The EVAP canister purge valve--Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
    • The fuel sender assembly and/or seal--Refer to Fuel Sender Assembly Replacement .
    • The FTP sensor seal--Refer to Fuel Tank Pressure Sensor Replacement .
    • The fill limiter vent valve, pressure relief valve, rollover valves, and/or fuel tank--Refer to Fuel Tank Replacement .

Did you find and repair a leak?

--

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 the engine and allow the engine to idle.
  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 Diagnostic Aids

Go to Step 16

9
  1. Monitor the pressure gage on J 41413 .
  2. Disconnect the purge pipe at the EVAP canister.

Does the EVAP system pressure decrease?

--

Go to Step 14

Go to Step 10

10
  1. Monitor the pressure gage on J 41413 .
  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 sensor voltage with a scan tool.

Is the FTP sensor voltage more than the specified value?

4.3 V

Go to DTC P0453

Go to Step 15

12

Inspect the vacuum source tot he EVAP purge valve for blockage, cuts, or disconnects. Repair as necessary.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

13

Repair the 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 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 Canister Purge Solenoid Valve Replacement .

Did you complete the replacement?

--

Go to Step 18

--

17

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

Did you complete the repair?

--

Go to Step 19

--

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

    3. Important: DO NOT exceed the specified value in this 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 EVAP system pressure remain constant?

5 in H2O

Go to Step 19

Go to Step 7

19
  1. Monitor the pressure on the J 41413 .
  2. Command the EVAP purge valve to 50 percent with a scan tool.

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