GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 DTC 🢒 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
    • DTC 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) 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 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 malfunction indicator lamp (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 the J 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. To repair a blockage in the EVAP system refer to Evaporative Emission System Cleaning .
    •  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 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: The following steps require the J 41413 EVAP Pressure and Purge Station and the J 41415-40 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 fuel fill cap adaptor.
  2. Connect the pressure and purge station and the vehicle fuel fill cap to the fuel fill cap adaptor.
  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 and purge 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 and purge station value to the scan tool FTP sensor value.

Does EVAP pressure and purge 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. The following step require the J 41416 Ultrasonic Leak Detector .
  2. With the J 41413 , continuously pressurize the EVAP system.

    3. Important:  Partially lowering the fuel tank may be necessary to inspect components located in the upper portion of the tank.

  3. With the J 41416 , inspect for leaks in the following locations:
    4. • The EVAP system purge pipe
    • The EVAP vapor pipe
    • The EVAP vent hose/pipe
    • The fuel fill pipe/hose and fuel fill cap
    •  Refer to Filler Tube Replacement .
    • The EVAP canister
    • The EVAP canister vent valve
    • The EVAP canister purge valve Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
    • The fuel sender assembly and/or seal
    • The FTP sensor seal
    • The fill limiter vent valve, pressure relief valve, rollover valves, and/or fuel tank
    • Refer to Fuel Tank Replacement .

Did you locate a leak?

--

Go to Step 17

Go to Diagnostic Aids

8

  1. Attach a vacuum gage to the EVAP purge valve purge pipe port.
  2. Start the engine and allow to idle.
  3. With a scan tool, command the EVAP purge valve to 50 percent.

Does the vacuum gage show an increase in vacuum?

--

Go to Diagnostic Aids

Go to Step 14

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

Does the EVAP system pressure decrease?

--

Go to Step 15

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 16

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 12

12

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

Did you complete the replacement?

--

Go to Step 17

--

13

Repair for a pinched or obstructed EVAP vapor pipe.

Did you complete the repair?

--

Go to Step 17

--

14

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

Did you complete the replacement?

--

Go to Step 17

--

15

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

Did you complete the repair?

--

Go to Step 17

--

16

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

Did you complete the repair?

--

Go to Step 17

--

17
  1. Turn ON the ignition, with the engine OFF.
  2. With the scan tool, seal the EVAP system.
  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?

--

Go to Step 18

Go to Step 7

18
  1. Monitor the pressure gage on the J 41413 .
  2. With a scan tool, command the EVAP purge valve to 50 percent.

Does the EVAP system pressure decrease?

--

Go to Step 19

Go to Step 9

19
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 20

Go to Step 2

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