GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 4WD 🢒 DTC 🢒 DTC P0440 Evaporative Emission (EVAP) System

Object Number: 387281 Size: LF
Engine Controls Components
Fuel Level and Fuel Tank Pressure Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The evaporative system includes the following components:

    • The fuel tank
    • The EVAP vent solenoid
    • The fuel tank pressure sensor
    • The fuel pipes and hoses
    • The fuel vapor lines
    • The fuel cap
    • The EVAP canister
    • The purge lines
    • The EVAP canister purge solenoid valve
    • The EVAP service port

The evaporative emission system is checked by applying vacuum to the EVAP system and by monitoring for a vacuum decay. The PCM monitors the vacuum level through the fuel tank pressure sensor signal. At an appropriate time, the EVAP canister purge valve and the EVAP vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP canister purge valve will turn OFF, sealing the system. DTC P0440 will set because the PCM is not detecting the expected vacuum. This can be caused by the following components with the conditions listed below:

    • The fuel cap for the following conditions:
       - Missing
       - Malfunctioning
       - Incorrect
    • The fuel tank pressure sensor for the following conditions:
       - Disconnected
       - Malfunctioning
    • The EVAP purge line for the following conditions:
       - Disconnected
       - Damaged
       - Pinched
       - Blocked
    • The EVAP vent hose for the following conditions:
       - Disconnected
       - Damaged
    • The fuel tank vapor line for the following conditions:
       - Disconnected
       - Damaged
       - Pinched
       - Blocked
    • The EVAP canister purge solenoid valve for the following conditions:
       - Disconnected
       - Malfunctioning
    • The EVAP vent solenoid for the following conditions:
       - Disconnected
       - Malfunctioning
    • An open ignition feed circuit to the following components:
       - EVAP vent valve
       - Purge solenoid
    • A damaged EVAP canister
    • A leaking fuel sender assembly O-ring
    • A leak in the following items:
       - Fuel tank
       - Fuel filler neck

Conditions for Running the DTC
    • No active MAP DTCs
    • No active IAT DTCs
    • No active ECT DTCs
    • No active TP DTCs
    • No active oxygen sensor DTCs
    • No active fuel tank pressure DTCs
    • No active VSS DTCs
    • No active PCM memory DTCs
    • The BARO is more than 75 kPa
    • The start-up IAT is between 5°C and 29°C (41°F and 84°F)
    • The start-up ECT is between 5°C and 29°C (41°F and 84°F)
    • The start-up ECT is less than 8°C (14°F) above the Start-up IAT
    • The start-up IAT is less than 1.5°C (3°F) above the Start-up ECT
    • The fuel tank level is between 15 percent and 85 percent
    • The TP sensor is between 7 percent and 35 percent
    • The vehicle speed is less than 70 MPH (113 KPH)
    • The purge solenoid is enabled

Conditions for Setting the DTC

The EVAP system is unable to detect vacuum during the diagnostic test.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will illuminate.
    • The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information.
    • A history DTC stores.

Conditions for Clearing the MIL/DTC
    • The MIL will turn OFF after one ignition cycle in which the diagnostic runs a pass.
    • Freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.
    • Use a scan tool to clear the DTC.

Diagnostic Aids

Inspect for the following conditions:

    • A missing, loose, or damaged fuel cap.
    • Missing or damaged O-rings at the EVAP canister fuel vapor fittings and the purge line fittings.
    • A cracked EVAP canister.
    • Damaged or disconnected source vacuum line, EVAP purge line, vent hose, or fuel tank vapor line.
    • A poor connection at the PCM -- Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals.
    • Damaged harness -- Inspect the wiring harness to the EVAP vent solenoid, the EVAP purge solenoid, and the fuel tank pressure sensor for an intermittent, open, or short circuit.
    • A kinked, pinched, or plugged vacuum source, EVAP purge, or fuel tank vapor line. Verify that the lines are not restricted.

Inspect for charcoal particles. Refer to Evaporative Emission System Cleaning before starting repairs.

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

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

  1. If a vent solenoid or an EVAP canister purge valve electrical malfunction is present, the purge system will not operate correctly. Repairing the electrical malfunction will usually correct the condition that set DTC P0440.

    2.

  2. This step tests the fuel tank pressure sensor at the ambient pressure.

    3.

  3. This step determines whether or not the EVAP system is sealed sufficiently in order to be pressurized. If the system is not sufficiently sealed, locate and correct the large leak before continuing with the diagnosis.

    4.

  4. This step verifies that the fuel tank pressure sensor accurately reacts to the EVAP system pressure changes.

    5.

  5. This step tests for a stuck closed EVAP canister purge solenoid valve.

    6.

  6. This step ensures that a sufficient source vacuum is present at the EVAP canister purge solenoid valve.

    7.

  7. This step insures proper system integrity.

DTC P0440-Evaporative Emission (EVAP) Control System

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.

Is DTC P0452, P0453 or P0461 also set?

--

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 3

3
  1. Visually and physical inspect for the following conditions:
    2. • A missing fuel cap
    • A loose fuel cap
    • A malfunctioning fuel cap
  2. Replace or tighten the fuel cap if necessary.

Did you find a missing, loose, or malfunctioning, or fuel cap?

--

Go to Step 20

Go to Step 4

4
  1. Command the EVAP canister purge valve ON and OFF with the scan tool.
  2. Command the vent solenoid ON and OFF with the scan tool.

Does the purge valve and the vent solenoid click when they are commanded ON and OFF?

--

Go to Step 5

Go to Powertrain Control Module Outputs Diagnosis

5
  1. Turn OFF the ignition.
  2. Disconnect the vapor line from the fuel tank at the EVAP canister.
  3. Turn ON the ignition, leaving the engine OFF.
  4. Observe the Fuel Tank Pressure sensor value with the scan tool.

Is the Fuel Tank Pressure within the specified value range?

-0.32 - +0.32 kPa

(-1.28 - +1.28 in. H2O)

Go to Step 7

Go to Ste 6

6
  1. Turn OFF the ignition.
  2. Inspect the EVAP vapor line from the fuel tank to EVAP canister for the following conditions:
    3. • A pinched vapor line
    • A kinked vapor line
    • A plugged vapor line
  3. If a problem is found, repair the condition as necessary.

Did you find and correct the condition?

--

Go to Step 20

Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage

or

DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage

7

Important:: Before continuing with this diagnosis, zero the EVAP Pressure and the Vacuum gauges on the J 41413 EVAP pressure/purge Diagnostic Station . Also, read the temperature variation instructions. Refer to the tool operating instructions.

  1. Reconnect all the EVAP hardware that was previously disconnected.
  2. Command the EVAP vent solenoid ON , or closed, with the scan tool.
  3. Connect the J 41413 EVAP pressure/purge Diagnostic Station to the EVAP service port.

    4. Important: Do not exceed the pressure in the specified value.

  4. Attempt to pressurize the EVAP system to the specified value by using the J 41413 EVAP pressure/purge Diagnostic Station and monitor the pressure with the gauges on the station with the switch in the HOLD position.

Can the specified value be achieved?

1.25 kPa

(5 in. H2O)

Go to Step 8

Go to Step 10

8
  1. Maintain the Fuel Tank Pressure at the first specified value and monitor the pressure with the gauges on the station with the switch in the HOLD position.
  2. Observe the Fuel Tank Pressure value on the scan tool.

Does the Fuel Tank Pressure decrease to less than the second specified value within 2 minutes?

1.25 kPa

(5 in. H2O)

.96 kPa (3.85 in. H2O)

Go to Step 12

Go to Step 9

9

Important: Review the temperature variation instructions included with the J 41413 EVAP pressure/purge Diagnostic Station before performing this step.

  1. Turn OFF the ignition.
  2. Install the J 41415-40 Fuel Tank Cap Adapter.
  3. Connect the J 41413 EVAP pressure/purge Diagnostic Station to the Fuel Tank Cap Adapter
  4. Turn ON the ignition, with the engine OFF.
  5. Command ON the scan tool's EVAP SYSTEM SEAL function to seal the EVAP system.

    6. Important: Do not exceed the pressure given in the first specified value.

  6. Pressurize the EVAP system to the first specified value by using the J 41413 EVAP pressure/purge Diagnostic Station and monitor the pressure by using the gauge on the station.

Does the pressure decrease to less than the second specified value within 2 minutes?

3.74 kPa

(15 in. H2O)

2.49 kPa

(10 in. H2O)

Go to Step 10

Go to Step 11

10
  1. Disconnect the following lines from the EVAP canister.
    2. • The fuel tank vapor line
    • The EVAP purge line
  2. Block the canister fitting for the fuel tank vapor line.
  3. Connect a hand vacuum pump to the canister fitting for the EVAP purge line.
  4. Ensure that the EVAP vent solenoid is still commanded ON, or closed.
  5. Attempt to apply the specified vacuum to the EVAP canister.

Can vacuum be achieved and maintained at the specified value?

17 kPa

(5 in. Hg)

Go to Step 15

Go to Step 14

11
  1. Visually and physically inspect for the following conditions:
    2. • A restricted fuel tank vapor line
    • A restricted EVAP purge line
    • A restricted purge valve
  2. If you find a problem, repair the condition the as necessary.

Did you find and correct the condition?

--

Go to Step 20

Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage

or

DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage

12
  1. Disconnect the throttle body to EVAP emission canister purge valve vacuum hose from the EVAP canister purge valve.
  2. Connect a hand vacuum pump to the EVAP canister purge valve vacuum source fitting.
  3. Apply the specified amount of vacuum to the EVAP canister purge valve.
  4. Command the EVAP purge valve ON with the scan tool.

Does the EVAP canister purge valve release the vacuum?

34 kPa

(10 in Hg)

Go to Step 13

Go to Step 17

13
  1. Connect the vacuum gauge on the J 41413 EVAP pressure/purge Diagnostic Station to the vacuum source line.
  2. Start the engine.
  3. Stabilize the engine RPM near the first specified value.
  4. Momentarily snap the throttle open and then allow the throttle to return to idle.

Is the vacuum more than the second specified value when the throttle was snapped open and then closed?

2,500 RPM

33.86 kPa

(10 in. Hg)

Go to Diagnostic Aids

Go to Step 18

14
  1. Visually and physically inspect for the following conditions:
    2. • A disconnected vent hose
    • A damaged vent hose
    • A damaged EVAP canister
  2. If you find a problem, repair the condition the as necessary.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

15
  1. Turn OFF the ignition.
  2. Visually and physically inspect for the following conditions:
    3. • A malfunctioning fuel cap
    • An incorrect fuel cap
    • A leaking fuel tank filler neck
    • A disconnected fuel tank vapor line
    • A leaking fuel tank vapor line
    • A disconnected EVAP purge line
    • A damaged EVAP purge line
    • The quick connect O-rings for the EVAP lines.
  3. If you find a problem, repair the condition the as necessary.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

16
  1. Reconnect all the EVAP hardware that was previously disconnected.
  2. Turn ON the ignition, with the engine OFF.
  3. Command the EVAP vent solenoid ON with the scan tool.
  4. With the station connected to the EVAP service port, continuously attempt to pressurize the EVAP system by leaving the station control knob in the pressurized position.
  5. Use the J 41416 ultrasonic leak detector to locate and repair any leaks in the EVAP system. It may be necessary to partially lower the fuel tank in order to examine the top tank connections.

Did you complete the repair?

--

Go to Step 20

--

17
  1. Turn OFF the ignition.

    2. Notice: The EVAP canister may have released carbon particles which caused this part to fail and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service.

  2. Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
  3. If carbon particles are found in the component, refer to Evaporative Emission System Cleaning .

Did you complete the replacement?

--

Go to Step 20

--

18
  1. Turn OFF the ignition.
  2. Locate and repair the cause of no source of vacuum to the EVAP canister purge valve.

Did you complete the repair?

--

Go to Step 20

--

19
  1. Turn OFF the ignition.

    2. Notice: The EVAP canister may have released carbon particles which caused this part to fail and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service.

  2. Replace the EVAP vent solenoid. Refer to Evaporative Emission Vent Valve Replacement .
  3. If carbon particles are found in the component refer to Evaporative Emission System Cleaning .

Did you complete the replacement?

--

Go to Step 20

--

20

Important: Review the temperature variation instructions included with J 41413 EVAP pressure/purge Diagnostic Station before performing this step.

  1. Reconnect all the EVAP hardware that was previously disconnected.
  2. Turn ON the ignition, with the engine OFF.
  3. Command the EVAP vent solenoid ON, or closed, with the scan tool.

    4. Important: Do not exceed the pressure given in the first specified value.

  4. Pressurize the EVAP system to the first specified value with the J 41413 EVAP pressure/purge Diagnostic Station, and monitor the pressure by using the gauge on the station.
  5. Switch the rotary switch on the station to HOLD and observe the EVAP pressure gauge.

Does the pressure decrease to less than the second specified value within 2 minutes?

3.74 kPa

(15 in. H2O)

2.49 kPa

(10 in. H2O)

Go to Step 3

Go to Step 21

21
  1. Use a scan tool to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK