For 1990-2009 cars
Engine Controls Components
Cell 20: EVAP Controls, IAC, PSP Switch
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The PCM monitors the positive or negative pressure in the fuel tank using the fuel tank pressure sensor. Under certain engine operating conditions, the PCM turns ON the EVAP pressure switching solenoid in order to monitor the positive or negative pressure in different sides of the EVAP system. The PCM is able to detect any abnormal conditions by the fluctuation of this pressure. The diagnostics performed by the fuel tank pressure sensor can warn the driver of a malfunction in the EVAP system by illuminating the MIL. The EVAP control system prevents the emission of the fuel vapors. The fuel vapor generated in the fuel tank while driving or idling enters the EVAP canister where a charcoal element absorbs and stores the fuel vapor. The EVAP canister is purged (cleaned) by the PCM controlled EVAP canister purge solenoid valve. The EVAP canister purge solenoid valve releases the fuel vapors into the intake manifold to be burned in the combustion process.

### Conditions for Setting the DTC

The pressure indicated in the EVAP canister does not drop during purge control (EVAP canister purge solenoid valve is ON).

OR

The pressure indicated in the EVAP canister remains very low when compared to atmospheric pressure during purge cut off (EVAP canister purge solenoid valve is OFF).

### 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 PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.

• | A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.

• | A DTC can be cleared by using the scan tool Clear Information function.

### Diagnostic Aids

If a DTC P0441 is the only EVAP DTC set, the most likely cause is an inoperable EVAP canister purge solenoid valve. Inspect the EVAP canister purge solenoid valve carefully for faulty connections and erratic operation.

An intermittent DTC P0441 can be caused by a faulty EVAP canister. An EVAP canister that has released carbon particles can cause the EVAP canister purge solenoid valve to fail (leak) intermittently. Inspect the EVAP purge system for carbon contamination before returning the vehicle to service. Refer to Evaporative Emission System Cleaning .

A DTC P0441 is more likely to set during city driving. Avoid operating the vehicle on the highway when validating a DTC P0441.

Clear the DTCs. 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 P0441 under Last Test Failed. If there is no DTC P0441 indicated, the DTC is intermittent and the purge system diagnostic is indicating OK at this time.

The DTC P0441 diagnostic checks for EVAP system leaks on the purge side of the EVAP system. A fault in any of the EVAP system components, except the fuel tank and filler pipe, can cause a DTC P0441 to set. Check for any of the following conditions:

• | A faulty fuel tank pressure sensor

• | A faulty EVAP canister purge solenoid valve

• | A faulty EVAP pressure switching solenoid

• | A faulty or leaking EVAP canister

• | Damaged or leaky hoses, lines, or fittings

• | A faulty or leaking fill limiter vent valve (FLVV)

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

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

• | Backed out terminals.

• | Improper mating of terminals.

• | Broken electrical connectors locks.

• | Improperly formed or damaged terminals

• | Faulty terminal to wire connections.

• | Physical damage to the wiring harness.

• | A broken wire inside the insulation.

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

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.

If the DTC 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 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. This step checks for the correct function of the EVAP canister purge solenoid valve.

3. This step checks whether a fuel tank pressure sensor malfunction is present. The input signal voltage of the fuel tank pressure sensor should indicate atmospheric pressure, 3.0 to 3.6 volts, with the fuel tank filler cap removed. The fuel tank pressure sensor voltage will vary with atmospheric pressure. A typical voltage at sea level is 3.2-3.3 volts.

4. This step checks for a possible leak in the EVAP system from the fuel tank to the fuel tank pressure sensor. Normal operation of the EVAP canister prevents EVAP system pressure from exceeding 3.3 mm Hg (6.0 in H2O). The purpose of this inspection is to determine whether 5 to 6 inches of H2O can be obtained and held for at least 2 minutes.

5. When the EVAP pressure switching solenoid turns ON, fuel tank vapor pressure is applied to the fuel tank pressure sensor through the EVAP canister. Turning ON the EVAP pressure switching solenoid while pressurizing the fuel tank should cause the fuel tank pressure sensor voltage to increase.

6. This step checks for EVAP system leaks. By connecting the EVAP canister purge solenoid hose and the EVAP vapor line together, the fuel tank, the fuel filler hose assembly, and the EVAP purge line can be pressurized and checked for leaks. Be sure to check all connections and sealing points for leaks.

7. This step checks for the correct function of the EVAP pressure switching solenoid.

8. This step checks for a condition that causes fuel vapor pressure to remain trapped at the fuel tank pressure sensor.

9. This step checks for leaks in the fuel supply system. By plugging the ORVR vent line and the EVAP vapor line, the fuel tank, the fuel filler hose assembly, and the fuel tank components can be pressurized and checked for leaks. Be sure to check all connections and sealing points for leaks.

10. This step checks whether the malfunction that caused the DTC P0441 is still present. Operating the vehicle in check mode enhances the PCM's diagnostic capabilities. The EVAP Purge diagnostic can be monitored on the scan tool under the MIL/System Status selection of System Information. When the EVAP Purge test displays a YES status (indicating that the purge system diagnostic is completed) check for a DTC P0441 in the Last Test Failed screen of the scan tool. If there is no DTC P0441 displayed the EVAP purge system diagnostic has run and passed, indicating that no malfunction was present this time. DTCs MUST BE CLEARED in order to view the CURRENT STATUS of the system diagnostics being performed. Do not forget that the MIL/System Status tests only indicate that the test has run, not whether the test passed or failed. The Last Test Failed screen must be checked for related DTCs in order to determine the outcome of the diagnostic test involved. For additional information on check mode operation refer to Powertrain Control Module Diagnosis.

11. The EVAP canister has component parts that cannot be diagnosed or tested on the vehicle. The EVAP canister should be inspected and tested for correct operation by performing the EVAP canister inspection procedures in EVAP Control System Diagnosis.

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 |

1. Install a scan tool.
2. Check for DTCs.

Is a DTC P0450 present?

--

Go to DTC P0450 Fuel Tank Pressure Sensor Circuit

Go to Step 3

3 |

1. Visually and physically inspect all of the following components for cracks, leaks, or damage:

• | The EVAP canister purge solenoid valve

• | The fuel tank pressure sensor

• | The EVAP pressure switching solenoid

• | The EVAP canister

• | The EVAP system lines, hoses, and fittings

2. Repair as necessary.

Was repair necessary?

--

Go to Step 43

Go to step 4

4 |

1. Disconnect the EVAP canister purge solenoid valve electrical connector.
2. Turn ON the ignition, leaving the engine OFF.
3. Probe terminal 2 of the EVAP canister purge solenoid valve electrical connector (harness side), with a test lamp connected to ground.

Did the test lamp illuminate?

--

Go to Step 5

Go to Step 7

5 |

1. Disconnect both vacuum hoses from the EVAP canister purge solenoid valve.
2. Blow air into the lower port of the EVAP canister purge solenoid valve.
3. Air should not pass through the solenoid and out the upper port.
4. Using a fused jumper wire, supply battery positive voltage to terminal 2 of the EVAP canister purge solenoid valve and ground to terminal 1 of the EVAP canister purge solenoid valve.
5. Blow air into the lower port of the EVAP canister purge solenoid valve.
6. Air should pass through the solenoid and out of the upper port.

Did the EVAP canister purge solenoid valve pass both tests?

--

Go to Step 6

Go to Step 34

6 |

1. Turn ON the ignition, leaving the engine OFF.
2. Probe terminal 1 of the EVAP canister purge solenoid valve control circuit, engine harness side, with a test lamp connected to B+.

Did the test lamp illuminate?

--

Go to Step 40

Go to Step 8

7 | Repair the open in the ignition positive voltage circuit of the EVAP canister purge solenoid valve. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 43 | --
8 | Measure the resistance of the EVAP canister purge solenoid valve with a DMM. Is the resistance of the EVAP canister purge solenoid valve within the specified value? | 27-33 ohms at 20°C (68°F) | Go to Step 9 | Go to Step 36
9 |

1. Loosen the fuel tank filler cap.
2. Remove the left side driver compartment kick panel.
3. Turn ON the ignition, leaving the engine OFF.
4. Backprobe the fuel tank pressure sensor input circuit (BLU wire) at C221 with a DMM connected to ground.

Does the DMM read within the specified value?

3.0-3.6 volts

Go to Step 10

Go to Step 19

10 |

1. Remove the fuel filler cap and install the gas cap adapter (J 41415-30) to the fuel filler pipe.
2. Connect the EVAP pressure/purge cart (J 41413) to the gas cap adapter.
3. Pressurize the EVAP system, with the EVAP pressure/purge cart, to the specified value and switch to HOLD.

Does the EVAP system hold the specified pressure for at least 2 minutes?

8.5-10.5 mm Hg (4.5-5.5 in. H2O)

Go to Step 12

Go to Step 11

11 |

1. Check for a leak in the following components:

• | The EVAP pressure switching solenoid

• | The 3 vacuum/vapor hoses connected to the EVAP pressure switching solenoid

2. Repair or replace as necessary.

Was a repair necessary?

--

Go to Step 43

Go to Step 27

12 |

1. Install a scan tool.
2. Select the EVAP pressure switching solenoid Output Control feature on the scan tool.
3. Pressurize the EVAP system, with the EVAP pressure/purge cart, to the first specified value and switch to HOLD.
4. Turn ON the EVAP pressure switching solenoid with the scan tool.
5. Backprobe the fuel tank pressure sensor input circuit (BLU wire) at C221 with a DMM connected to ground.

Is the voltage indicated by the DMM within the second specified value?

8.5-10.5 mm Hg (4.5-5.5 in. H2O)

4.2-4.6 volts

Go to Step 13

Go to Step 14

13 | Refer to the Evaporative Emission Control System Operation Description for the EVAP system hose routing schematic used in the following procedure.

1. Remove the ORVR vent line from the EVAP canister and plug the hose. In order to see how to release the ORVR vent line connection, refer to Evaporative Emission Canister Replacement .
2. Remove the EVAP vapor line and the purge line (to the canister purge solenoid) from the EVAP canister.
3. Connect the EVAP vapor line and the purge line together using a section of vacuum pipe.
4. Attempt to pressurize the EVAP system to the specified value with the EVAP pressure/purge cart (J 41413) and HOLD.
5. Locate any leaks in the EVAP and fuel supply systems using the ultrasonic leak detector (J 41416). If necessary lower the fuel tank in order to check the condition of the fill limiter vent valve and the rollover valve. Be sure to check the fuel sender assembly for a correct seal.

Were any EVAP or fuel supply system leaks found?

56 mm Hg (30 in. H2O)

Go to Step 29

Go to Step 37

14 |

1. Disconnect the EVAP pressure switching solenoid electrical connector.
2. Turn ON the ignition, leaving the engine OFF.
3. Probe terminal 2 of the EVAP pressure switching solenoid electrical connector (harness side), with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 15

Go to Step 18

15 |

1. Probe terminal 1 of the EVAP pressure switching solenoid control circuit with a test lamp to B+.
2. Turn ON the EVAP pressure switching solenoid with the scan tool.

Did the test lamp illuminate only when the EVAP pressure switching solenoid was commanded ON?

--

Go to Step 16

Go to Step 17

16 |

1. Connect the EVAP pressure switching solenoid electrical connector.
2. Disconnect the three vacuum hoses from the EVAP pressure switching solenoid.
3. Blow air into the inboard port (fuel tank pressure sensor port) of the EVAP pressure switching solenoid.
4. Air should pass through the valve and out the single port that goes to the EVAP canister.
5. Turn ON the EVAP pressure switching solenoid with the scan tool.
6. Blow air into the inboard port (fuel tank pressure sensor port) of the EVAP pressure switching solenoid.
7. Air should pass through the solenoid and out of the outboard port.

Did the EVAP pressure switching solenoid pass both tests?

--

Go to Step 42

Go to Step 32

17 |

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

Was a repair necessary?

--

Go to Step 43

Go to Step 30

18 | Repair the open in the ignition positive voltage circuit of the EVAP pressure switching solenoid. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 43 | --
19 |

1. Disconnect the vapor pressure supply hose to the fuel tank pressure sensor.
2. Check the fuel tank pressure sensor input circuit voltage at C221 with the DMM.

Is the voltage within the specified value?

3.0-3.6 volts

Go to Step 20

Go to Step 21

20 |

1. Repair the cause of the trapped vapor pressure to the fuel tank pressure sensor. Check for any of the following conditions:

• | Pinched, crushed, or restricted EVAP lines and hoses

• | Blocked or restricted EVAP components

• | Faulty EVAP solenoids or EVAP canister. Refer to Evaporative Emission Control System Diagnosis .

2. Repair as necessary.

Is the action complete?

--

Go to Step 43

--

21 |

1. Turn OFF the ignition.
2. Disconnect the fuel tank pressure sensor electrical connector.
3. Turn ON the ignition, leaving the engine OFF.
4. Measure the voltage from the fuel tank pressure sensor connector cavity 3 (harness side), using a DMM.

Does the DMM read the specified value?

5.0 volts

Go to Step 22

Go to Step 23

22 | Measure the voltage from the fuel tank pressure sensor connector cavity 2 (harness side) with a DMM. Does the DMM read near the specified value? | 4.9 volts | Go to Step 25 | Go to Step 24
23 |

1. Check the fuel tank pressure sensor reference voltage circuit for an open or short.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 43

Go to Step 41

24 |

1. Check the fuel tank pressure sensor input circuit for an open or short.
2. Check that the input circuit is not shorted to the sensor ground circuit.
3. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 43

Go to Step 41

25 | Probe the fuel tank pressure sensor connector cavity 1 (harness side) with a test lamp connected to battery voltage. Does the test lamp illuminate? | -- | Go to Step 33 | Go to Step 26
26 |

1. Check for an open fuel tank pressure sensor ground circuit.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 43

Go to Step 41

27 | Refer to the Evaporative Emission Control System Operation Description for the EVAP system hose routing schematic used in the following procedure.

1. Remove the ORVR vent line from the EVAP canister and plug the hose.
2. Remove the EVAP vapor line from the EVAP canister and plug the hose.
3. Attempt to pressurize the EVAP system to the specified value with the EVAP pressure/purge cart (J 41413) and HOLD.
4. Locate any leaks in the EVAP and fuel supply systems using the ultrasonic leak detector (J 41416). If necessary lower the fuel tank in order to check the condition of the fill limiter vent valve and the rollover valve. Be sure to check the fuel sender assembly for a correct seal.

Were any EVAP or fuel supply system leaks found?

56 mm Hg (30 in. H2O)

Go to Step 29

Go to Step 28

28 | Replace the malfunctioning/leaking EVAP canister. Is the action complete? | -- | Go to Step 43 | --
29 | Repair or replace the leaking EVAP system or fuel tank component. Is the action complete? | -- | Go to Step 43 | --
30 | Measure the resistance of the EVAP pressure switching solenoid with a DMM. Is the resistance of the EVAP pressure switching solenoid less than the specified value? | 27 ohms at 20°C (68°F) | Go to Step 41 | Go to Step 31
31 | Replace the EVAP pressure switching solenoid and the PCM. Refer to Evaporative Emission Pressure Switching Solenoid Replacement and Powertrain Control Module Replacement Is the action complete? | -- | Go to Step 43 | --
32 | Replace the EVAP pressure switching solenoid. Refer to Evaporative Emission Pressure Switching Solenoid Replacement . Is the action complete? | -- | Go to Step 43 | --
33 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | Go to Step 43 | --
34 | Measure the resistance of EVAP canister purge solenoid valve with a DMM. Is the resistance of the EVAP canister purge solenoid valve less than the specified value? | 27 ohms at 20°C (68°F) | Go to Step 36 | Go to Step 35
35 | Notice: The EVAP canister may have released carbon particles which caused this part to fail and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service. Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Is the action complete?

--

Go to Step 43

--

36 | Replace the EVAP canister purge solenoid valve and the PCM. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement and Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 43 | --
37 |

1. Perform the scan tool Clear DTC Information function.
2. Place the vehicle into Check Mode using the scan tool.
3. Operate the vehicle within the Freeze Frame conditions as specified or until the EVAP Purge test is complete. Refer to the Test Description.
4. Check for DTCs.

Did a DTC P0441 set?

--

Go to Step 38

Fault Not Present-Go to Diagnostic Aids

38 |

1. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement .
2. Visually and physically inspect the EVAP canister for cracks or signs of damage.
3. Perform a comprehensive inspection of the EVAP Canister. Refer to Evaporative Emission Control System Diagnosis .
4. Replace the EVAP canister if the canister is damaged or fails any inspections.

Was the EVAP canister replaced?

--

Go to Step 43

Go to Step 39

39 |

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

Was a repair necessary?

--

Go to Step 43

Go to Step 41

40 |

1. Check the EVAP canister purge solenoid valve control circuit for a short to ground.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 43

Go to Step 41

41 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 43 | --
42 | Repair the restriction or blockage in the following components:

1. The fuel tank pressure sensor
2. The hose from the EVAP pressure switching solenoid to the fuel tank pressure sensor
3. The hoses from the EVAP canister to the EVAP pressure switching solenoid

Is the action complete?

--

Go to Step 43

--

43 |

1. Perform the scan tool Clear DTC Information function.
2. Operate the vehicle within the Freeze Frame data that set the original DTC.
3. Review the scan tool data and check for DTCs. The repair is complete if no DTCs are stored.

Are any DTCs displayed on scan tool?

--

Go to the applicable DTC table

System OK