GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Safari - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 DTC P0440

Description

The evaporative emission (EVAP) large leak test applies vacuum to the evaporative emission (EVAP) system and monitors vacuum decay. The control module monitors the fuel tank pressure (FTP) sensor signal in order to determine the vacuum decay rate. At an appropriate time, the control module turns the EVAP canister purge valve ON, open, and the EVAP vent valve ON, closed. This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the control module turns the purge valve OFF, closed, sealing the system, and monitors the FTP sensor input in order to determine EVAP system vacuum. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, DTC P0440 will set.

Conditions for Running the DTC
    • DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1111, 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) of each other.
    • 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 illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
    •  Use the J 41413 EVAP Pressure/Purge Diagnostic 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. To repair a blockage in the EVAP system, refer to Evaporative Emission System Cleaning .
    •  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.

  1. This step verifies that a failure condition is active.

    2.

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

    3.

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

    4.

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

DTC P0440

Step

Action

Values

Yes

No

Schematic Reference: Emission 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 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 17

Go to Step 4

4

  1. With a scan tool, capture and record the Failure Records data and clear the DTCs.
  2. Perform the Service Bay Test. Refer to Service Bay Test .

Does the scan tool indicate that the service bay test passed?

--

Go to Diagnostic Aids

Go to Step 5

5

Important: Always zero the EVAP pressure and vacuum (in H2O) gauges on the J 41413 EVAP Pressure/Purge Diagnostic Station before proceeding with diagnosis.

  1. Install the J 41415-40 Fuel Fill Cap Adaptor.
  2. Connect the J 41413 and the vehicle fuel fill cap to the J 41415-40 .
  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 J 41413 rotary switch to the OFF/HOLD position. Monitor the pressure gauge for 1 minute.

Did you obtain and hold the specified value?

5 in H2O

Go to Step 6

Go to Step 8

6

Compare the J 41413 value to the scan tool (FTP) fuel tank pressure sensor value.

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

--

Go to Step 7

Go to Step 13

7
  1. With the J 41413 , pressurize the EVAP system to the specified value.
  2. Rotate the J 41413 rotary valve to the OFF/HOLD position.
  3. Monitor the pressure gauge on J 41413 .
  4. With a scan tool, command the EVAP canister purge valve to 50 percent.

Does the EVAP system pressure decrease?

5 in H2O

Go to Step 9

Go to Step 10

8
  1. With the J 41413 , continuously pressurize the EVAP system.

    2. Important: The fuel tank may need to be partially lowered in order 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:
    3. • The EVAP system purge pipe--Refer to Evaporative Emission Hoses/Pipes Replacement - Engine .
    • 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 fuel tank pressure (FTP) sensor seal--Refer to Fuel Tank Pressure Sensor Replacement .
    • The fill limiter vent valve, pressure relief valve, rollover valve, or fuel tank--Refer to Fuel Tank Replacement .

Did you locate and repair the system?

--

Go to Step 17

Go to Diagnostic Aids

9

  1. Disconnect the EVAP purge pipe from the EVAP canister purge valve.
  2. Install the J 41413 vacuum hose on the EVAP canister purge valve port.
  3. Start the engine.
  4. Run the engine between 1200-1500 RPM.
  5. With a scan tool command the EVAP canister purge valve to 50 percent.

Does the EVAP pressure/purge diagnostic station vacuum gauge measure above the specified value?

12 in Hg

Go to Diagnostic Aids

Go to Step 15

10
  1. Monitor the pressure gauge on the J 41413 .
  2. Disconnect the EVAP purge pipe from the EVAP purge valve.

Does the EVAP system pressure decrease?

--

Go to Step 15

Go to Step 11

11
  1. Monitor the pressure gauge on the J 41413 .
  2. Disconnect the purge pipe at the EVAP canister.

Does the EVAP system pressure decrease?

--

Go to Evaporative Emission System Cleaning

Go to Step 12

12
  1. Monitor the pressure gauge on the J 41413 .
  2. Disconnect the EVAP vapor line from the EVAP canister.

Does the EVAP system pressure decrease?

--

Go to Step 16

Go to Step 14

13

Replace the fuel tank pressure (FTP) sensor. Refer to Fuel Tank Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 17

--

14

Repair for a pinched or obstructed EVAP vapor pipe.

Did you complete the repair?

--

Go to Step 17

--

15

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

Did you complete the replacement?

--

Go to Step 17

--

16

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

Did you complete the replacement?

--

Go to Step 17

--

17

Perform the Service Bay Test. Refer to Service Bay Test .

Does the scan tool indicate that the service bay test passed?

--

Go to Step 18

Go to Step 5

18

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