DTC P0440 Evaporative Emission (EVAP) System. Chevrolet S10 Pickup

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1996 🢒 S10 Pickup - 2WD 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 DTC P0440 Evaporative Emission (EVAP) System

Handling ESD Sensitive Parts Notice
Engine Controls Components
EVAP and EGR System
OBD II Symbol Description Notice

Circuit Description

The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The PCM monitors the vacuum level via the fuel tank vacuum sensor input. At a calibrated time, the EVAP purge solenoid and the EVAP vent solenoid turn ON. This allows the engine vacuum to draw a small vacuum on the entire evaporative emission system. Whenever a sufficient vacuum level cannot be achieved, a large leak or a faulty EVAP purge solenoid is indicated.

Conditions for Setting the DTC

•	The BARO is greater than 75 kPa.

•	The intake air temperature is between 4° C and 30° C at engine start up.

•	The engine coolant temperature is between 4° C and 30° C at engine start up.

•	The start-up ECT sensor is not more than 7°C (12°F) greater than start-up intake air temperature.

•	The fuel tank level is between 40 % and 90 %.

•	The TP sensor is between 9 and 35 %.

•	The engine run time is greater than 120 seconds.

•	The EVAP purge solenoid is at 50% PWM within 65 seconds of engine start-up.

•	The EVAP system is unable to achieve or maintain a vacuum during the diagnostic test. The amount of decay will vary with the fuel level.

•	One or more of the following DTCs are not set P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134 and P1133.

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 malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault.

•	A history DTC will clear after 40 consecutive warm up cycles without a fault.

•	Use a scan tool to clear the DTCs.

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 Carbon Particle Removal from EVAP System 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 the technician to complete some basic checks and store the Freeze Frame Data and the Failure Records on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurs. Refer to this information on the scan tool later.

If a vent solenoid or EVAP purge solenoid electrical fault is present, the purge system will not operate correctly. Repairing the electrical fault will very likely correct the condition that set DTC P0440.

Checks the fuel tank vacuum sensor at ambient pressure.

This makes the PCM zero the fuel tank pressure sensor.

Determine whether or not the EVAP system can be sealed sufficiently to be pressurized. If not, the large leak must be located and corrected before continuing with the diagnosis.

Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.

Checks for a stuck closed EVAP purge solenoid.

Ensures that a sufficient source vacuum is present at the EVAP purge solenoid.

Step

Action

Value(s)

Yes

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

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Was DTC P0460 also set?

Go to DTC P0460 Fuel Level Sensor Circuit

Go to Step 3

Visually inspect the fuel cap looking for a missing or loose condition.
Replace or tighten as necessary.

Was a loose or missing fuel cap found?

Go to Step 20

Go to Step 4

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

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

Go to Step 5

Go to Powertrain Control Module Outputs Diagnosis

Turn the ignition OFF.
Remove the fuel cap.
Turn the ignition ON.

Is the Fuel Tank Pressure at the specified value?

0 in. H2O (± 1 in H2O)

Go to Step 8

Go to Step 6

Has the battery been disconnected?

Go to Evaporative Emission Control System Diagnosis

Go to Step 7

Disconnect the battery.

Is the action complete?

Go to Step 5

Important: Before continuing with the diagnosis, zero the EVAP pressure and vacuum gauges on the EVAP pressure/purge cart Enhanced EVAP Pressure Purge Diagnostic Cart (refer to the tool operating instructions).

Reinstall the fuel cap.
Using the scan tool, command the EVAP vent valve ON (Closed).
Connect the EVAP pressure/purge cart Enhanced EVAP Pressure Purge Diagnostic Cart to the EVAP service port.
Attempt to pressurize the EVAP system to the specified value using the EVAP pressure/purge cart Enhanced EVAP Pressure Purge Diagnostic Cart (monitor the pressure using the gauge on the cart).

Can the specified value be achieved?

5 in. H2O (± 1 in H2O)

Go to Step 9

Go to Step 10

Maintain the specified EVAP pressure.
Observe the Fuel Tank Pressure on the scan tool.

Is the Fuel Tank Pressure at the specified value?

5 in. H2O

5 in. H2O ( ±2 in. H2O)

Go to Step 12

Go to Step 11

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

Can the specified vacuum be maintained?

5 in. Hg

Go to Step 15

Go to Step 14

Visually and physically check for the following conditions:

•	Restricted fuel tank vapor line

•	Restricted EVAP purge line

If a problem is found, repair as necessary. Refer to Diagnostic Aids.

Was a problem found?

Go to Step 20

Go to Evaporative Emission Control System Diagnosis

Disconnect the throttle body to the EVAP emission canister purge valve vacuum hose from the EVAP canister purge valve.
Connect a hand held 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 canister purge valve ON using a scan tool.

Does the EVAP canister purge valve release the vacuum?

10 in. Hg (34 kPa)

Go to Step 13

Go to Step 17

Connect the in. Hg vacuum gauge on the Enhanced EVAP Pressure Purge Diagnostic Cart to the vacuum source line.
Start the engine.
Run the engine above the specified value.
Observe the source vacuum level.

Is the source vacuum level greater than the specified value?

2000 RPM

15 in. Hg

Go to Step 20

Go to Step 18

Visually and physically check for the following conditions:

•	Vent hose disconnected or damaged

•	EVAP canister damaged

If a problem is found, repair as necessary. Refer to Diagnostic Aids.

Was a problem found?

Go to Step 20

Go to Step 19

Visually and physically check for the following conditions:

•	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. Refer to Diagnostic Aids.

Was a problem found?

Go to Step 20

Go to Step 16

Using the scan tool, command the EVAP vent valve ON (Closed).
With the J 41413 Enhanced EVAP Pressure Purge Diagnostic Cart connected to the EVAP service port attempt to pressurize the EVAP system by leaving the cart control knob in the pressurized position.
Using the ultrasonic leak detector J 41416 Enhanced EVAP Ultrasonic Leak Detector , repair the leak in the EVAP system. It may be necessary to partially lower the fuel tank to examine the top tank connections. Refer to Diagnostic Aids.

Is the action complete?

Go to Step 20

Replace the EVAP canister purge valve. Refer to Diagnostic Aids. Refer to Evaporative Emission Canister Purge Solenoid .

Is the action complete?

Go to Step 20

Repair the cause of no source vacuum to the EVAP canister purge valve. Refer to Diagnostic Aids.

Is the action complete?

Go to Step 20

Replace the EVAP vent solenoid. Refer to Diagnostic Aids. Refer to EVAP Vent Valve Replacement .

Is the action complete?

Go to Step 20

Important: Review the temperature variation instructions included with the J 41413 before performing this step.

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 specified value using the EVAP pressure/purge cart Enhanced EVAP Pressure Purge Diagnostic Cart .
Monitor the pressure 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 specified value within 2 min?

15 in. H2O

10 in. H2O

System OK

Go to Step 16