DTC P0440 Evaporative Emission (EVAP) System. Chevrolet Chevy Suburban 4WD

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1998 🢒 Chevy Suburban 4WD - RHD 🢒 DTC 🢒 DTC P0440 Evaporative Emission (EVAP) System

EVAP/PCV - Comp Loc Figure
Engine Controls Schematics
OBD II Symbol Description 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 vapor lines

•	The fuel cap

•	The evaporative emission canister

•	The purge lines

•	The EVAP purge solenoid

The evaporative leak detection diagnostic strategy is based on applying the vacuum to the EVAP system and monitoring the vacuum decay. The VCM monitors the vacuum level via the fuel tank vacuum sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid turn ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or a malfunctioning EVAP purge solenoid is indicated. The following conditions can cause this problem and set a DTC P0440:

•	A missing, malfunctioning, improperly installed, or loose fuel cap

•	A disconnected or malfunctioning fuel tank pressure sensor

•	A disconnected, damaged, pinched, or blocked EVAP purge line

•	A disconnected or damaged EVAP vent hose

•	A disconnected, damaged, pinched, or blocked fuel tank vapor line

•	A disconnected or malfunctioning EVAP purge solenoid

•	A disconnected or malfunctioning EVAP vent solenoid

•	An open ignition feed circuit to the EVAP vent or purge solenoid

•	A damaged EVAP canister

•	A leaking fuel sender assembly O-ring

•	A leaking fuel tank or fuel filler neck

Conditions for Running the DTC

•	No active MAP sensor DTCs

•	No active TP sensor DTCs

•	No active VS DTCs

•	No active O2 sensor DTCs

•	No active ECT sensor DTCs

•	No active IAT sensor DTCs

•	DTC P0125 not active

•	The system voltage is between 10-17 volts

•	The fuel level is between 12.5 % and 87 %

•	The ECT is between 4°C-30°C(39°F-86°F)

•	The IAT is between 4°C-30°C(39°F-86°F)

•	The cold start temperature difference (ECT minus IAT) is less than

-	1.5°C(35°F) when the IAT is greater than the ECT or

-	8°C(46°F) when the ECT is greater than the IAT

-	The BARO is greater than 73 kPa

Conditions for Setting the DTC

The EVAP system is unable to generate a vacuum greater than a calibrated value over a specified period of time.

Action Taken When the DTC Sets

•	The VCM illuminates the MIL during the second consecutive drive cycle in which the diagnostic reports a fail.

•	The VCM will set the DTC and records the operating conditions at the time the diagnostic fails. The VCM stores the failure information in the scan tools Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

•	The MIL will turn OFF after one ignition cycle in which the diagnostic runs without a fault.

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

•	A scan tool can clear the DTC(s).

Diagnostic Aids

Check for the following conditions:

•	A loose, missing, damaged, or improperly installed fuel cap

•	Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings

•	A loose, damaged or misaligned fuel filler tube or fuel filler vent hose

•	A cracked or punctured EVAP canister

•	A damaged or disconnected EVAP purge line, vent hose or fuel tank vapor line

•	A kinked, pinched or plugged EVAP Purge Line, or Fuel Tank Vapor Line.

•	A poor connection at the VCM: Inspect the harness connectors for the following conditions:

-	Backed out terminals

-	Improper mating

-	Broken locks

-	Improperly formed or damaged terminals

-	Poor terminal to wire connection

•	A damaged harness: Inspect the wiring harness to the EVAP vent solenoid EVAP purge solenoid and the fuel tank pressure sensor for an intermittent open or short circuit

Refer to Evaporative Emission Control System Diagnosis 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 be set occurs. This may assist in diagnosing the condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

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

This step determines if the EVAP system has a restriction or leak.

This step determines if there is a restriction in the Fuel Tank Vapor Line or Canister.

This step checks for a restriction in the EVAP Canister.

Step

Action

Value(s)

Yes

Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Is DTC P0446, P0452, or P0453 set?

Go to applicable DTC table

Go to Step 3

Turn OFF the ignition.
Install a scan tool.
Remove the fuel cap.
Turn ON the ignition.
Observe the Fuel Tank Pressure on the scan tool.

Is the Fuel Tank Pressure at the specified value?

-1-1 in.H2O

Go to Step 4

Go to Fuel Tank Pressure Sensor Diagnosis

Important: Before continuing with the diagnosis, zero the EVAP Pressure and Vacuum gauges on the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413. Refer to the tool operating instructions.

Important: Make sure the fuel cap is secured properly. A poorly installed or loose fuel cap can cause DTC P0440.

Install the fuel cap
Connect the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413 to the EVAP service port.
Using the scan tool, command the EVAP vent valve ON (Closed).
Attempt to pressurize the EVAP system using the Cart.
Monitor pressure using gauge on Cart for 2 minutes.

Can the specified value be obtained and held?

5 in.H2O

Go to Step 5

Go to Step 6

Maintain fuel tank pressure at 5 inches of H2O (Turn the rotary switch on the cart to the HOLD position).
Observe the Fuel Tank Pressure on the scan tool.

Is the Fuel Tank Pressure within the specified value?

3-7 in.H2O

Go to Step 9

Go to Step 8

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 Valve is still commanded ON (Closed).
Attempt to apply vacuum to the EVAP canister.

Can the specified value of vacuum be obtained and held?

5 in.Hg

Go to Step 12

Go to Step 7

Leave system connected as in step 6.
Disconnect the Vent hose at the Vent Valve.
Plug end of the Vent hose.
Using the hand vacuum pump apply vacuum up to the specified value.

Can the specified value of vacuum be obtained and held?

5 in.Hg

Go to Step 17

Go to Step 11

Disconnect Fuel Tank Vapor Line from the Canister.
Attempt to pressurize the EVAP system using the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413.
Monitor pressure using gauge on cart.

Can the specified value of pressure be obtained and held?

5 in.H2O

Go to Step 18

Go to Step 15

Disconnect Purge Line at the Canister.
Connect the in. Hg vacuum gauge on the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413 to the Purge Line.
Start engine
Command EVAP Purge Solenoid Valve to 100%.

Is the vacuum gauge at or above the specified value?

12 in.Hg

Go to Diagnostic Aids

Go to Step 10

Disconnect Purge Line from the Purge Solenoid Valve.
Connect the in. Hg vacuum gauge on the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413 to the Purge Solenoid Valve.
Start engine
Command EVAP Purge Solenoid Valve to 100%.

Is the vacuum gauge at or above the specified value?

12 in.Hg

Go to Step 14

Go to Step 16

Check the Vent hose for possible cause of vacuum leak and repair as necessary.

Was a repair necessary?

Go to Step 19

Go to Step 18

Check for the following:

•	Missing or faulty fuel cap.

•	Disconnected or leaking fuel Tank Vapor Line.

•	Disconnected or damaged EVAP Purge Line.

If a problem is found, repair as necessary.

Was a problem found?

Go to Step 19

Go to Step 13

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

Using the scan tool, command the EVAP Vent Valve ON.
With the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413 connected to the EVAP service port continuously attempt to pressurize the EVAP system by leaving the cart control knob in the pressurize position.
Using the Enhanced EVAP Ultrasonic Leak Detector J 41416, locate the leak in the EVAP system. It may be necessary to partially lower the fuel tank in order to examine the connections on the top of the fuel tank . Refer to Diagnostic Aids.
Repair the leak in the EVAP system.

Is the action complete?

15 in. H2O

Go to Step 19

Repair restriction in EVAP Purge Line.

Is action complete?

Go to Step 19

Repair restriction in Fuel Tank Vapor Line.

Is action complete?

Go to Step 19

Replace the EVAP Purge Solenoid Valve. Refer to Diagnostic Aids. Refer to EVAP Canister Purge Solenoid Valve Replacement in Repair Instructions.

Is the action complete?

Go to Step 19

Replace the EVAP Vent Valve. Refer to Diagnostic Aids. Refer to EVAP Vent Valve Replacement (EVAP) in Repair Instructions.

Is the action complete?

Go to Step 19

Replace EVAP Canister. Refer to Evaporative Emission Canister Replacement in Repair Instructions.

Is the action complete?

Go to Step 19

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

Turn the ignition ON leaving the engine OFF.
Using the scan tool, command the EVAP Vent Valve ON (Closed).
Pressurize the EVAP system to the first specified value using the Enhanced EVAP Pressure Purge Diagnostic Cart J 41413 (monitor pressure using the gauge on the cart).
Turn the rotary switch on the cart to the HOLD position 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 2

Go to Step 20

Use the scan tool in order to select the DTC and the Clear DTC Information functions.
Perform the Service Bay Test for EVAP.

Was the test performed and passed?

Go to Step 21

Go to Step 2

Use the scan tool in order to display the Capture Info and the Review Capture Info functions.

Are there any DTCs displayed that have not been diagnosed?

Go to applicable DTC table

System OK