DTC P0455 Evaporative Emission (EVAP) System Leak Detected. Chevrolet Metro 2001

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2001 🢒 Metro 🢒 DTC 🢒 DTC P0455 Evaporative Emission (EVAP) System Leak Detected

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

Circuit Description

The leak detection diagnostic strategy for the EVAP control system is based on applying a vacuum to the EVAP system and monitoring any decay. The PCM monitors the vacuum level via the fuel tank pressure sensor input. The PCM turns the EVAP purge valve and the EVAP vent solenoid on, allowing manifold pressure to draw a small vacuum on the EVAP system. If sufficient vacuum cannot be sustained over a period of time, a large leak or a malfunction is indicated and DTC P0455 sets.

The EVAP control system that is defined by Federal regulation includes the following components:

•	The fuel tank

•	The EVAP vent solenoid

•	The fuel tank pressure sensor

•	Fuel pipes and hoses

•	Vapor lines

•	The fuel filler cap

•	The pressure control valve of the EVAP tank

•	The EVAP canister

•	Purge lines

•	The 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.

•	The fuel tank level is between 25 and 75 percent.

Conditions for Setting the DTC

•	The fuel tank pressure that is 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).

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

Conditions for Clearing the DTC

•	The MIL turns OFF after 3 consecutive passing trips without a fault present.

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

•	Use the Clear DTC Information function of the scan tool, 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 P0455 to set. If the EVAP Purge test passes, the cause of the DTC P0455 is probably intermittent. Perform the Clear DTC Information function with the scan tool . 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 scan tool indicates YES, check for DTC P0455 under Last Test Failed. If DTC P0455 is not indicated, the EVAP Purge diagnostic is indicating OK at this time.

Usually, DTC P0455 will set during city driving. Avoid operating the vehicle for long periods on the highway when validating a DTC P0455.

A DTC P0455 can be caused by any of the following conditions:

•	A fuel filler cap that is faulty or loose

•	A damaged source vacuum line or a disconnected source vacuum line

•	A damaged EVAP purge line or a leaking EVAP purge line

•	A damaged EVAP vent hose or a leaking EVAP vent hose

•	A damaged fuel tank vapor line or a leaking fuel tank vapor line

•	A damaged EVAP purge valve or a leaking EVAP purge valve

•	A damaged EVAP pressure valve or a leaking EVAP pressure valve

•	A damaged EVAP vent solenoid or a leaking EVAP vent solenoid

•	A cracked EVAP canister or a punctured EVAP canister

•	A leaking O-ring in the fuel sender assembly

•	A leaking fuel tank or a leaking fuel filler neck

•	Restrictions in the EVAP hoses, in the lines, or in the components

•	A faulty pressure control valve in the fuel tank

•	A faulty fuel pressure sensor

•	Fuel level sensor malfunction

A fuel level sensor that indicates an incorrect fuel level may cause the EVAP leak check diagnostic to run at the wrong time. An EVAP leak check diagnostic that runs at the wrong time may falsely indicate a leak. Check the fuel level sensor accuracy by observing the scan tool parameter before and after adding 3.8 liters (1 gallon) of fuel. The scan tool display should increase about 7 percent after adding the fuel. If a change of 7 percent 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 system electrical circuit. Inspect the wiring harness and the components for any of the following conditions:

•	Backed out terminals

•	Incorrect mating of terminals

•	Broken electrical connector locks

•	Incorrectly formed terminals or damaged terminals

•	Faulty terminal-to-wire connections

•	Physical damage to the wiring harness

•	A broken wire inside the insulation

•	Corrosion of electrical connections, of splices, or of terminals

If the DTC cannot be duplicated, the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC 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 basic checks, and to store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data that was taken when the fault occurred. The information is stored in the scan tool for later reference.

This step checks for other EVAP DTCs. Before diagnosing DTC P0440, diagnose any other DTCs .

This step checks the components that supply manifold vacuum to the EVAP canister purge valve.

This step checks the operation of the EVAP canister purge valve. The duty cycle control of the EVAP purge valve is disabled by the PCM when any DTCs are stored, when engine speed is indicated, and until the engine has reached a normal operating temperature of at least 80°C (176°F).

This step checks the operation of the pressure control valves in the fuel tank . The pressure control valves will regulate the tank pressure to approximately 18.6-25 mm Hg (10-14 in H2O) when the EVAP vent solenoid is open. If the pressure is less than the specified value after 2 minutes, check for a faulty pressure control valve, for a faulty EVAP pressure control valve, or for a system leak .

This step checks the operation of the EVAP tank pressure control solenoid valve. If the EVAP pressure control valve is turned ON, the fuel tank pressure bypasses the fuel tank pressure valves, and drops to 0 if the EVAP canister vent is open.

Use the ultrasonic leak detector in order to locate any leaks after pressurizing the EVAP system. If you were sent here from step 9, the leak may be between the fuel tank pressure valves and the fuel tank or in the fuel tank. If you were sent here from step 10, the leak may be between the EVAP canister purge valve and the fuel tank pressure valves.

A EVAP canister vent solenoid that is leaking or inoperative prevents the EVAP system from holding pressures greater than 18.6 mm Hg (10 in H2O). Inspect the electrical circuit of the EVAP canister vent solenoid for an open that could prevent the solenoid from turning ON.

This step checks for the correct operation of the fuel tank pressure sensor. With the fuel tank filler pipe open to the atmosphere, the fuel tank pressure sensor should read near zero. The pressure sensor reading will vary with changes in atmospheric pressure. The specified value in step 13, is typical of atmospheric pressure near sea level. If the scan tool reading is significantly more or less than the specified value, the fuel tank pressure sensor may be faulty. The fuel tank pressure sensor is diagnosed in DTC P0450.

This step determines if the malfunction that caused the DTC P0455 is still present. The DTC P0455 diagnostic can be monitored on the scan tool under the MIL/System Status selection of System Information. If the EVAP Purge test displays YES, check for DTC P0455 in the Last Test Failed screen of the scan tool. If DTC P0455 is not displayed, the EVAP purge system diagnostic has run and passed, indicating that the malfunction was not present this time. DTCs must be cleared in order to view the current status of the system diagnostics that are being performed. The MIL/System Status tests only indicate that the test has run, not if the test passed or failed. The Last Test Failed screen must be checked for related DTCs in order to determine the result of the diagnostic test that is involved.

A short to ground will keep the EVAP pressure control valve open and cause the system to fail. Inspect the control circuit and the PCM for a short to ground. Repair the circuit if necessary. The output control of the EVAP pressure control valve is disabled if any DTCs are stored, if engine speed is indicated, and until the engine reaches an operating temperature of at least 80°C (176°F).

This step checks the operation of the EVAP canister vent solenoid. The output control of the EVAP vent solenoid is disabled if DTCs are stored, if engine speed is indicated, and until the engine reaches an operating temperature of at least 80°C (176°F).

This step checks the operation of the EVAP tank pressure control solenoid valve. The output control of the EVAP pressure control valve is disabled if any DTCs are stored, if engine speed is indicated, and until the engine has reached an operating temperature of at least 80°C (176°F).

This step tests for an EVAP pressure control valve that is stuck open or leaking.

This step checks the EVAP canister for restrictions.

The DTC P0455 diagnostic can be monitored on the scan tool in the MIL/System Status selection of System Information. If the EVAP purge test displays YES, check for DTC P0455 in Last Test Failed on the scan tool. If DTC P0455 is not listed, the diagnostic has run and passed indicating that the malfunction was not present this time. DTCs must be cleared in order to view the current status of the system diagnostic that is being performed. The MIL/System Status tests only indicate that the test has run, not if the test passed or failed. The Last Test Failed screen must be checked for related DTCs in order to determine the result of the diagnostic test.

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

Connect a scan tool, and inspect for any DTCs.

Are any other EVAP codes set with the exception of a P0440?

Go to the applicable DTC tables

Go to Step 3

Visually inspect the entire evaporative system for the following:

•	A loose fuel filler cap or a faulty fuel filler cap

•	Loose hose connections

•	Damaged hoses or deteriorated hoses

•	Restricted hoses

•	Missing components or damaged components

•	Faulty terminal connections on all of the related components

Repair as necessary.

Was a repair necessary?