DTC P0440 Evaporative Emission (EVAP) System. GMC Truck Sonoma Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P0440 Evaporative Emission (EVAP) System

Engine Controls Components
Cell 20: 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.

Conditions for Running the DTC

•	No active MAP DTC's

•	No active IAT DTC's

•	No active ECT DTC's

•	No active TP DTC's

•	No active Oxygen Sensor DTC's

•	No active Fuel Tank Pressure DTC's

•	No active VSS DTC's

•	No active PCM Memory DTC's

•	The BARO is more than 75 kPa.

•	The Start-up ECT and IAT are between 4°C and 30°C (39°F and 86°F).

•	The Start-up ECT is less than 8°C (14°F) above Start-up IAT.

The Start-up IAT is less than 1.5°C (3°F) above Start-up ECT.

•	The fuel level is between 15 percent and 85 percent.

•	The TP sensor is between 7 percent and 35 percent.

•	The Vehicle Speed is less than 70MPH (113KPH).

•	The engine is running.

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.

•	The freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.

Diagnostic Aids

Check for the following conditions:

•	A missing, loose, or damage 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.

Check 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.

The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.

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 very likely correct the condition that set DTC P0440.

This step checks the fuel tank pressure sensor at the ambient pressure.

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

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

This step checks for a stuck closed EVAP canister purge valve.

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

This step insures a proper system integrity.

Step

Action

Value(s)

Yes

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

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn ON the ignition leaving the engine OFF.
Install a scan tool.

Is DTC P0452, P0453, P0460, P0462 or P0463 also set?

Go to applicable DTC table

Go to Step 3

Visually/Physically check the fuel cap for any missing or loose conditions.
Replace or tighten the fuel cap if necessary.

Was a loose or a missing fuel cap found?

Go to Step 18

Go to Step 4

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

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

Go to Step 5

Go to Powertrain Control Module Outputs Diagnosis

Remove the fuel cap.
Observe the fuel tank pressure value on the scan tool.

Is the fuel tank pressure at the specified value?

-2.4 to 2.4 mmHg

(-1.28 to 1.28 in. H2O)

Go to Step 6

Go to

DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage

DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage

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

Reinstall the fuel cap.
Command the EVAP vent solenoid ON (closed) with the scan tool.
Connect the EVAP pressure/purge cart J 41413 to the EVAP service port.

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

Attempt to pressurize the EVAP system to the specified value by using the EVAP pressure/purge cart J 41413 (monitor the pressure with the gauges on the cart with the switch in the HOLD position).

Can the specified value be achieved and maintained?

5 in. H2O

Go to Step 7

Go to Step 8

Maintain the fuel tank pressure at the first specified value.
Observe the fuel tank pressure value on the scan tool.

Is the fuel tank pressure at the second specified value?

12 mmHg

(6.42 in. H2O)

7.2 to 16.8 mmHg

(3.85 to 8.99 in. H2O)

Go to Step 10

Go to Step 9

Disconnect the fuel tank vapor line and the EVAP purge line from the EVAP canister.
Block the canister fitting for the fuel tank vapor line.
Connect a hand vacuum pump to the canister fitting for the EVAP purge line.
Ensure that the EVAP vent solenoid is still commanded ON (closed).
Attempt to apply the specified vacuum to the EVAP canister.

Can vacuum be achieved and maintained at the specified value?

5 in. Hg

Go to Step 13

Go to Step 12

Visually/physically check for the following conditions:

•	A restricted fuel tank vapor line

•	A restricted EVAP purge line

If a problem is present, repair the problem as necessary.

Was a problem found?

Go to Step 18

Go to

DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage

DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage

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

Does the EVAP canister purge valve release the vacuum?

10 in of Hg (34 kPa)

Go to Step 11

Go to Step 15

Connect the in. Hg vacuum gauge on the EVAP pressure/purge cart J 41413 of the vacuum source line.
Start the engine.
Stabilize the engine RPM near the first specified value.
Momentarily snap the throttle open and then allow the throttle to return to idle.

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

2500 RPM

10 in. Hg

Go to Diagnostic Aids

Go to Step 16

Visually/physically check for the following conditions:

•	A disconnected or a damaged vent hose

•	A damaged EVAP canister

If a problem is present, repair the problem as necessary.

Was a repair necessary?

Go to Step 18

Go to Step 17

Visually/physically check for the following conditions:

•	A missing or a malfunctioning fuel cap

•	A disconnected or a leaking fuel tank vapor line

•	A disconnected or a damaged EVAP purge line

•	The quick connect O-rings for the EVAP lines.

If a problem is present, repair the problem as necessary.

Was a repair necessary?

Go to Step 18

Go to Step 14

Reconnect all the EVAP hardware that was previously disconnected.
Command the EVAP vent solenoid ON with the scan tool.
With the cart connected to the EVAP service port, continuously attempt to pressurize the EVAP system by leaving the cart control knob in the pressurized position.
Using the ultrasonic leak detector J 41416 , 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).

Is the action complete?

Go to Step 18

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

Is the action complete?

Go to Step 18

Locate and repair the cause of no source of vacuum to the EVAP canister purge valve.

Is the action complete?

Go to Step 18

Replace the EVAP vent solenoid. Refer to Evaporative Emission Vent Valve Replacement .

Is the action complete?

Go to Step 18

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

Reconnect all the EVAP hardware that was previously disconnected.
Turn ON the ignition switch leaving the engine OFF.
Command the EVAP vent solenoid ON (closed) with the scan tool.

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

Pressurize the EVAP system to the first specified value with the EVAP pressure/purge cart J 41413 . Monitor the pressure by using the gauge on the cart.
Switch the rotary switch on the cart to HOLD and observe the EVAP pressure gauge.

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

15 in. H2O

10 in. H2O

Go to Step 3

Go to Step 19

Clear the DTCs with the scan tool.
Start the engine.
Idle the engine at the normal operating temperature.
Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that the diagnostic ran and passed?

Go to Step 20

Go to Step 2

Check to see if any additional DTC are set.

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

Go to the applicable DTC table

System OK