For 1990-2009 cars
EGR Valve and EVAP Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The evaporative emission (EVAP) control system leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The powertrain control module (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 valve, allowing the engine manifold pressure to draw a small vacuum on the entire EVAP system. If sufficient vacuum cannot be sustained over a given period of time, a small leak or a malfunction is suspected and DTC P0440 sets.

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

• | The fuel tank

• | The EVAP vent valve

• | The fuel tank pressure sensor

• | The fuel pipes and hoses

• | The vapor lines

• | The fuel filler cap

• | The fuel tank pressure control valve

• | The EVAP canister

• | The purge lines

• | The EVAP canister purge valve

### Condition for Running the DTC

• | The engine coolant temperature is between 70°C and 110°C (158°F-230°F)

• | The intake air temperature is between -7°C and +70°C (19°F-158°F).

• | The barometric pressure (BARO) is more than 75 kPa.

• | The fuel tank level is less than 75 percent.

• | The engine is operating in Closed Loop.

• | The engine speed is between 1,000 and 3,000 RPM (A/T), or 1,000 and 3,500 RPM (M/T).

### Conditions for Setting the DTC

A fuel tank pressure change indicates the EVAP purge accumulation time is more than 360 seconds.

The diagnostic may take up to 20 minutes to run.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL) after 2 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 3 consecutively passing trips without a fault present.

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

• | Perform the scan tool Clear DTC Information function in order to clear the DTC.

### Diagnostic Aids

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

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

Check for any of the following conditions:

• | A cracked or punctured EVAP canister.

• | A damaged or disconnected source vacuum line, EVAP purge line, vent hose, or fuel tank vapor line.

• | A faulty or erratic fuel level sensor can cause DTC P0440 to set.

• | A faulty or erratic fuel tank pressure sensor can cause DTC P0440 to set.

• | A faulty EVAP canister purge valve

• | A faulty EVAP canister vent valve

• | A faulty EVAP tank pressure control vacuum valve

For functional checks of the components listed above, refer to Evaporative Emission Control System Diagnosis .

If a DTC P0440 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P0440 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0440 appears in the Not Ran Since Code Cleared list, the P0440 diagnostic has not yet run. When the DTC P0440 does not appear in the Not Ran Since Code Cleared list, the P0440 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the P0440 diagnostic has passed. The DTCs MUST be cleared in order to view the Current STATUS of the Not Ran Since Code Cleared list. DO NOT FORGET that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for CURRENT or PENDING status, in order to determine the outcome of the diagnostic test involved.

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

• | Any backed-out terminals

• | Any improper mating of terminals

• | Any broken electrical connector locks

• | Any improperly formed or damaged terminals

• | Any faulty terminal-to-wire connections

• | Any physical damage to the wiring harness

• | A broken wire inside the insulation

• | Any corrosion of the electrical connections, the splices, or the 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.

1. 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.

2. If any EVAP diagnostic trouble codes other than DTC P0455 are set, diagnose those DTCs first.

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

4. This step checks the control circuit of the pressure control vacuum valve . A short to ground will keep the pressure control vacuum valve open and cause the system to fail. The output control of the pressure control vacuum valve is disabled by the PCM when any DTCs are stored and when engine speed is indicated.

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

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

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

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

9. 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.

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

11. This step checks the EVAP canister for blockage or restrictions.

12. This step dtermines whether the malfunction that caused DTC P0440 is still present. Driving the vehicle under these conditions will verify whether the fault is present. After performing the scan tool Clear DTC Information function, the DTC P0440 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P0440 appears in the Not Ran Since Code Cleared list, the P0440 diagnostic has not yet run. When DTC P0440 does not appear in the Not Ran Since Code Cleared list, the P0440 diagnostic has run. If the MIL is NOT illuminated and there is no Pending DTC Status in DTC Information, the P0440 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any EVAP codes set other than DTC P0455? | -- | Go to Diagnostic Trouble Code (DTC) List | Go to Step 3
3 | Visually inspect the entire EVAP control system for any of the following conditions:

• | Any loose hose connections

• | Any damaged or deteriorated hoses

• | Any clogged hoses

• | Any missing or damaged components

• | Any faulty terminal connections on any related components

• | A loose or faulty fuel cap

Was a problem found?

--

Go to Step 21

Go to Step 4

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.

1. Remove the fuel tank pressure (FTP) control valve.

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

2. 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

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

1. Blow hard through the valve from the tank port side. Air should flow through the valve to the canister port.
2. Apply the specified value of vacuum to the vacuum port of the FTP control valve using a hand held vacuum pump.
3. With the vacuum applied, blow gently through the tank side port. Air should flow easily through to the canister port.

Did the FTP control valve pass both checks?

51 kPa (15 in Hg)

Go to Step 6

Go to Step 29

6 |

1. Turn ON the ignition, leaving the engine off.
2. Command the EVAP tank pressure control valve ON with the scan tool.
3. Disconnect the vacuum hoses from the EVAP tank pressure control valve.
4. Blow air through the fuel tank pressure control valve side of the EVAP tank pressure control valve.

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

--

Go to Step 7

Go to Step 8

7 |

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

• | Any restrictions

• | Any cracks

• | Any leaks

2. Repair any problems found during the above checks.

Was a repair necessary?

--

Go to Step 35

Go to Step 10

8 |

1. Turn OFF the ignition.
2. Disconnect the electrical connector from the EVAP tank pressure control valve .
3. Turn ON the ignition, leaving the engine off.
4. Probe the harness side of the electrical connector terminal 1 with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 23

9 |

1. Probe the harness side of the electrical connector terminal 2 with the test lamp connected to B+.
2. Command the EVAP tank pressure control valve OFF with the scan tool. The test lamp should not illuminate.
3. Command the EVAP tank pressure control valve ON with the scan tool. The test lamp should illuminate.

Does the test lamp indicate that the control circuit of the EVAP tank pressure control valve passed both checks?

--

Go to Step 33

Go to Step 32

10 |

1. Check for any of the following conditions at the EVAP canister purge valve:

• | No manifold vacuum from the intake manifold vacuum port

• | Any leaking or damaged vacuum hoses

• | Any restricted vacuum hoses or passages

2. Repair any problems found during the above checks.

Was a repair necessary?

--

Go to Step 35

Go to Step 11

11 |

1. Turn ON the ignition, leaving the engine off.
2. Disconnect the vacuum hoses to the EVAP canister purge valve from the intake manifold and from the EVAP canister.
3. Blow air into the vacuum hose that was disconnected from the EVAP canister. Air should not pass through the EVAP canister purge valve and exit from the intake manifold hose.
4. Command the EVAP canister purge valve ON and adjust the duty cycle to 100 percent with the scan tool.
5. Blow air into the vacuum hose that was disconnected from the EVAP canister. Air should pass through the EVAP canister purge valve and exit from the intake manifold hose.

Does the EVAP canister purge valve pass both inspections?

--

Go to Step 14

Go to Step 12

12 |

1. Turn ON the ignition, leaving the engine off.
2. Probe the ignition positive voltage circuit at the electrical connector terminal 1 of the the EVAP canister purge valve with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 13

Go to Step 23

13 |

1. Probe the control circuit for the EVAP canister purge valve at the electrical connector with a test lamp connected to B+.
2. Command the EVAP canister purge valve ON with the scan tool. Adjust the duty cycle from 0 to 100 percent while monitoring the test lamp.

Does the test lamp flash and then illuminate fully as the duty cycle reaches 100 percent?

--

Go to Step 31

Go to Step 30

14 |

1. Turn OFF the ignition.
2. Remove the canister hose from the EVAP canister vent valve.
3. Apply the specified amount of vacuum to the canister side of the EVAP canister vent valve using a hand vacuum pump.

Does the valve hold the vacuum?

51 kPa (15 in Hg)

Go to Step 27

Go to Step 15

15 |

1. Turn ON the ignition, leaving the engine off.
2. Command the EVAP canister vent valve ON using a scan tool.
3. Apply the specified value of vacuum to the canister side of the EVAP canister vent valve using a hand vacuum pump.

Does the valve hold the vacuum?

51 kPa (15 in Hg)

Go to Step 16

Go to Step 17

16 | While the EVAP canister vent valve is still holding vacuum from Step 15, use the scan tool to command the EVAP canister vent valve OFF. Did the vacuum decrease to the specified value? | 0 kPa (0 in Hg) | Go to Step 19 | Go to Step 24
17 |

1. Turn OFF the ignition.
2. Disconnect the electrical connector from the EVAP canister vent valve .
3. Turn ON the ignition, leaving the engine off.
4. Probe the harness side of terminal 1 of the EVAP canister vent valve with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 18

Go to Step 23

18 |

1. Command the EVAP canister vent valve ON with the scan tool.
2. Probe the harness side of terminal 2 of the EVAP canister vent valve with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 28

Go to Step 26

19 |

1. Turn ON the ignition, leaving the engine off.
2. Remove the fuel cap and install the gas cap adapter.
3. Connect the J 41413 EVAP pressure/purge diagnostic station to the gas cap adapter.
4. Apply vacuum to the pressure control valve vacuum port using a hand vacuum pump.
5. Command the EVAP canister vent valve ON with the scan tool.
6. Pressurize the EVAP system to the first specified value using the J 41413 EVAP pressure/purge diagnostic station. Monitor the pressure using the gauge on the cart.
7. Turn the rotary switch on the J 41413 EVAP pressure/purge diagnostic station to the HOLD position and observe the EVAP pressure gauge.

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

28 mm Hg (15 in. H2O)

18.6 mm Hg (10 in. H2O)

Go to Step 20

Go to Step 22

20 |

1. With the Step 19 conditions met, continually attempt to pressurize the EVAP system to the specified value.
2. Locate any leaks in the EVAP system using the J 41416 ultrasonic leak detector. In order to examine the top tank connections, partially lower the fuel tank.

Were any leaks found?

56 mm Hg (30 in. H2O)

Go to Step 21

Go to Step 22

21 | Replace any leaking or faulty EVAP control system components. Is the action complete? | -- | Go to Step 35 | --
22 |

1. Disconnect the vacuum hoses from the EVAP canister and block the vent valve port.
2. Using a hand held vacuum pump connected to the tank port, attempt to obtain the specified value of the vacuum pressure. The pressure should bleed through the canister and out the purge port with no restrictions.

Did the vacuum gauge indicate any pressure?

18.6 mm Hg (10 in H2O)

Go to Step 25

Go to Diagnostic Aids

23 | Repair the open in the ignition positive voltage circuit between terminal 1 and the main relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 35 | --
24 |

1. Check for a short to ground in the control circuit between the EVAP canister vent valve and the PCM.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 35

Go to Step 34

25 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Is the action complete? | -- | Go to Step 35 | --
26 |

1. Check for an open in the control circuit of the EVAP canister vent valve .
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 35

Go to Step 34

27 |

1. Inspect the vacuum hoses of the EVAP canister vent valve for restrictions.
2. Repair as necessary.

Was a repair necessary?

--

Go to Step 35

Go to Step 28

28 | Replace the EVAP canister vent valve. Refer to Evaporative Emission Canister Vent Solenoid Replacement . Is the action complete? | -- | Go to Step 35 | --
29 | Replace the FTP control valve. Refer to Fuel Tank Pressure Control Valve Replacement . Is the action complete? | -- | Go to Step 35 | --
30 |

1. Check for an open or a short in the control circuit of the EVAP canister purge valve .
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 35

Go to Step 34

31 | Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Is the action complete? | -- | Go to Step 35 | --
32 |

1. Check for an open or a short in the control circuit of the EVAP tank pressure control valve .
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 35

Go to Step 34

33 | Replace the EVAP tank pressure control valve. Refer to Evaporative Emission Tank Pressure Control Solenoid Valve Replace . Is the action complete? | -- | Go to Step 35 | --
34 | Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 35 | --
35 |

1. Perform the scan tool Clear DTC Information function and road test the vehicle within the Freeze Frame conditions that set the DTC or until the P0440 diagnostic test has run. Refer to the Test Description.
2. Review the scan tool data and check for DTCs. The repair is complete if no DTCs are stored.

Are any DTCs displayed on the scan tool?

--

Go to Diagnostic Trouble Code (DTC) List

System OK