DTC P0440 Evaporative Emission (EVAP) System. Chevrolet Metro 1998

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1998 🢒 Metro 🢒 DTC 🢒 DTC P0440 Evaporative Emission (EVAP) System

Engine Controls Components
Cell 20: EVAP Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The EVAP control system 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 pressure sensor input. The PCM turns ON the EVAP canister purge valve and the EVAP vent solenoid, allowing engine manifold pressure (vacuum) to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum cannot be sustained over a given period of time, a small leak (or a malfunction) is indicated and a DTC P0440 sets.

The EVAP control system as defined by federal regulation includes the following components:

•

Fuel tank

•	EVAP vent solenoid

•	Fuel tank pressure sensor

•	Fuel pipes and hoses

•	Vapor lines

•	Fuel filler cap

•	EVAP Tank Pressure Control Valve

•	EVAP canister

•	Purge lines

•	EVAP canister purge valve

Conditions for Running the DTC

•	Engine coolant temperature is 70°C to 110°C (158°F to 230°F).

•	Intake air temperature is -10°C to 50°C (14°F to 122°F).

•	Barometric pressure is greater than 75 kPa.

•	Fuel tank level is between 25 and 75%.

Conditions for Setting the DTC

•	Fuel tank pressure indicated is within a specified value.

•	Purge accumulation time is greater than 200 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) after two consecutive ignition cycles in which the diagnostic runs with the fault active.

•	The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

•	The MIL turns OFF after three consecutively passing trips without a fault present.

•	A History DTC clears after 40 consecutive warm-up cycles without a fault.

•	Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC.

Diagnostic Aids

The EVAP Purge diagnostic checks for many of the faults that can cause a DTC P0440 to set. If the EVAP Purge test passes, the cause of the DTC P0440 is probably intermittent. Clear the DTC information. Road test the vehicle while monitoring the EVAP Purge test in the MIL/System Status selection under System Information on the scan tool. When the EVAP Purge test indicates complete with a YES status, check for a DTC P0440 under Last Test Failed. If there is no DTC P0440 indicated the EVAP Purge diagnostic is indicating OK at this time.

A DTC P0440 is more likely to set during city driving. Avoid operating the vehicle for long periods on the highway when validating a DTC P0440.

A DTC P0440 can be caused by any of the following conditions:

•	Faulty or loose fuel filler (gas) cap

•	Damaged or disconnected source vacuum line.

•	Damaged or leaking EVAP purge line

•	Damaged or leaking EVAP vent hose

•	Damaged or leaking fuel tank vapor line

•	Leaking or faulty EVAP canister purge valve

•	Leaking or faulty EVAP tank pressure control solenoid valve

•	Leaking or faulty EVAP vent solenoid

•	Cracked or punctured EVAP canister.

•	Leaking fuel sender assembly O-ring

•	Leaking fuel tank or fuel filler neck

•	Blockage or restrictions in the EVAP hoses, lines, or components

•	Faulty fuel tank pressure control valve

•	Faulty or erratic fuel tank pressure sensor

•	Fuel level sensor malfunction

A fuel level sensor that indicates an incorrect fuel level may cause the EVAP control system leak check diagnostic to run at the wrong time. An EVAP control system leak check diagnostic that runs at the wrong time may indicate a leak when none exists. Check the fuel level sensor accuracy by observing the fuel level sensor scan tool parameter before and after adding 3.8 liters (1 gallon) of fuel. The scan tool display should increase about 7% after adding the fuel. If a change of 7% is not indicated, check the fuel level sensor by performing the diagnostic for a DTC P0461. Refer to DTC P0461 Fuel Level Sensor Performance .

For functional checks of the EVAP control system components, refer to Evaporative Emission Control System Diagnosis .

An intermittent malfunction may be caused by a fault in an EVAP control system electrical circuit. Inspect the wiring harness and components for any of the following conditions:

•	Backed out terminals.

•	Improper mating of terminals.

•	Broken electrical connector locks.

•	Improperly formed or damaged terminals.

•	Poor terminal to wire connections.

•	Physical damage to the wiring harness.

•	A broken wire inside the insulation.

•	Corrosion of electrical connections, splices, or terminals.

If the DTC P0440 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

Test Description

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

The Powertrain OBD System Check prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

This step checks for other EVAP DTCs. Diagnose any DTCs other than a DTC P0455 first.

This step checks the operation of the EVAP tank pressure control solenoid valve. The EVAP tank pressure control solenoid valve output control is disabled by the PCM when any DTCs are stored and when engine speed is indicated.

A short to ground will keep the EVAP tank pressure control solenoid valve open and cause the system to fail. The EVAP tank pressure control solenoid vacuum valve output control is disabled by the PCM when any DTCs are stored and when engine speed is indicated.

This step checks the components that supply manifold vacuum to the EVAP canister purge valve. A plugged or leaking EVAP canister surge tank could prevent vacuum from reaching the EVAP canister purge valve.

This step checks the operation of the EVAP canister purge valve. The EVAP canister purge valve duty cycle control is disabled by the PCM when any DTCs are stored and when engine speed is indicated.

This step checks the operation of the EVAP canister vent solenoid. The EVAP canister vent solenoid output control is disabled by the PCM when any DTCs are stored and when engine speed is indicated.

This step checks the EVAP canister vent solenoid control circuit. The EVAP canister vent solenoid output control is disabled by the PCM when any DTCs are stored and when engine speed is indicated.

This step uses tools from the EVAP Pressure/Purge Cart Diagnostic Station, in order to determine whether EVAP control system is sealed sufficiently to be pressurized. Any leak that is found must be located and repaired before continuing with the diagnosis.

Use the ultrasonic leak detector in order to locate any leaks after pressurizing the EVAP system.

This step checks the EVAP canister for blockage or restrictions.

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

Are any other EVAP codes set with the exception of a P0455?

Go to Appropriate DTC Tables

Go to Step 3

Visually inspect the entire EVAP control system for any of the following conditions:

•	Loose hose connections

•	Damaged or deteriorated hoses

•	Clogged hoses

•	Missing or damaged components

•	Faulty terminal (electrical) connections on any related components

•	Loose or faulty fuel cap

Was a faulty condition found?

Go to Step 21

Go to Step 4

Caution: Do not breathe the air through the EVAP component tubes or hoses. The fuel vapors inside the EVAP components may cause personal injury.

Remove the fuel tank pressure control valve. Refer to Fuel Tank Pressure Control Valve Replacement .

Important: There will be some resistance, but air should flow steadily through the valve.

Blow air through the valve from the canister port.

Did the air flow through the valve to the tank port side?

Go to Step 5

Go to Step 29

Important: The fuel tank pressure control valve will not allow air to flow from the tank port side to the canister port side until the pressure on the tank port side is greater than 3.5 kPa (0.5 psi).

Blow hard through the valve from the tank port side. Air should flow through the valve to the canister port side.
Apply the specified value of vacuum to the vacuum port of the fuel tank pressure control valve with a hand held vacuum pump.
With the vacuum applied, blow gently through the tank side port. Air should flow easily through the valve to the canister port side.

Did the fuel tank pressure control valve pass both checks?

15 in. Hg

Go to Step 6

Go to Step 29

Turn ON the ignition, leaving the engine OFF.
Command the EVAP tank pressure control solenoid valve ON, using a scan tool.
Disconnect the vacuum hoses from the EVAP tank pressure control solenoid valve.
Blow air through the fuel tank pressure control valve side of the EVAP tank pressure control solenoid valve.

Did the air pass through the valve and out through the manifold vacuum side?

Go to Step 7

Go to Step 8

Check the vacuum hoses and the intake manifold port for any of the following conditions:

•

Plugged

•

Cracks

•

Leaks

Repair any faulty conditions found in the checks above.

Was a repair necessary?