Refer to Engine Controls schematics
EVAP Controls,and IAC Valve
and
Fuel Supply System
.
Circuit Description
The powertrain control module (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 control the pressure in 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 by the PCM controlled EVAP canister purge valve. The EVAP canister purge valve releases the fuel vapors into the intake manifold to be burned in the combustion process.
Conditions for Running the DTC
| • | The engine coolant temperature is more than 70°C (158°F). |
| • | The vehicle has been driven for at least 20 minutes. |
| • | The fuel tank level is between 25 and 75 percent. |
Conditions for Setting the DTC
The fuel tank pressure sensor indicates no pressure increase in the fuel tank during conditions that normally cause an increased tank pressure.
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 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 DTCs P0441, P0446, or P0450 is set, diagnose those DTCs first. |
| • | A DTC P0440 is more likely to set during city driving. Avoid operating the vehicle on the highway when validating DTC P0440. |
| • | The DTC P0440 diagnostic checks for EVAP system leaks on the fuel tank side of the EVAP system. A fault in the fuel tank pressure sensor or a leak in any of the fuel tank components can cause DTC P0440 to set. Check for any of the following conditions: |
| - | A faulty fuel tank pressure sensor |
| - | A loose or faulty fuel tank filler cap |
| - | A factory correct fuel tank filler cap that meets OEM specifications |
| - | A faulty or leaking fill limiter vent valve |
| - | A leak in the fuel tank |
| - | A faulty or leaking EVAP canister |
| - | Any incorrectly routed or installed EVAP system lines and hoses |
| - | Any damaged or leaky hoses, lines, or fittings between the fuel tank, the fuel tank pressure sensor, and the EVAP canister |
| • | 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 the fuel tank pressure sensor electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions . |
If 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 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 a possible leak in the EVAP system. 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.
-
This step determines if a fuel tank pressure sensor malfunction is present. The input signal of the fuel tank pressure sensor should indicate atmospheric pressure with the fuel tank filler cap removed. The fuel tank pressure sensor will vary with atmospheric pressure. A typical pressure at sea level is between 0.0-0.99 mm Hg (0.0-0.5 in H2O).
-
This step checks for conditions that can cause the fuel vapor pressure to remain trapped at the fuel tank pressure sensor.
-
This step determines if the malfunction that caused the DTC P0440 is still present. Operating the vehicle in check mode enhances the PCMs 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 P0440 in the Last Test Failed screen of the scan tool. If there is no DTC P0440 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.
-
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.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | ||||||||||||
2 |
Is a DTC P0450 present? | -- | Go to Step 3 | |||||||||||
3 | Is a DTC P0441 or a DTC P0446 set along with a DTC P0440? | -- | Go to DTC P0441 Evaporative Emission (EVAP) System No Flow During Purge or to DTC P0446 Evaporative Emission (EVAP) Vent System Performance | Go to Step 4 | ||||||||||
4 |
Was repair necessary? | -- | Go to Step 21 | Go to Step 5 | ||||||||||
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 6 | Go to Step 16 | |||||||||||
Is the fuel tank pressure sensor within the specified range? | 0.0-0.99 mm Hg (0.0-0.5 in H2O) | Go to Step 15 | Go to Step 7 | |||||||||||
7 |
Is the fuel tank pressure sensor within the specified range? | 0.0-0.99 mm Hg (0.0-0.5 in H2O) | Go to Step 8 | Go to Step 9 | ||||||||||
Is the action complete? | -- | Go to Step 21 | -- | |||||||||||
9 |
Does the voltage equal the specified value? | 5.0 V | Go to Step 10 | Go to Step 11 | ||||||||||
10 | Measure the voltage from the fuel tank pressure sensor connector cavity 2 on the harness side with a DMM. Is the voltage near the specified value? | 4.9 V | Go to Step 13 | Go to Step 12 | ||||||||||
11 | Repair the open in the reference voltage circuit of the fuel tank pressure sensor between the sensor and SP259. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 21 | -- | ||||||||||
12 |
Was a repair necessary? | -- | Go to Step 21 | Go to Step 20 | ||||||||||
13 | Probe the fuel tank pressure sensor connector cavity 1 on the harness side with a test lamp connected to battery voltage. Does the test lamp illuminate? | -- | Go to Step 19 | Go to Step 14 | ||||||||||
14 | Repair the open in the ground circuit of the fuel tank pressure sensor between the sensor and S206. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 21 | -- | ||||||||||
Did DTC P0440 set? | -- | Go to Step 17 | Fault Not Present-Go to Diagnostic Aids | |||||||||||
Refer to the Evaporative Emission Control System Operation Description for the EVAP system hose routing diagram used in the following procedure.
Were any EVAP or fuel supply system leaks found? | 56 mm Hg (30 in. H2O) | Go to Step 18 | Go to Step 17 | |||||||||||
17 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Is the action complete? | -- | Go to Step 21 | -- | ||||||||||
18 | Repair or replace the leaking EVAP system or fuel tank component. Is the action complete? | -- | Go to Step 21 | -- | ||||||||||
19 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | Go to Step 21 | -- | ||||||||||
20 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 21 | -- | ||||||||||
21 |
Are any DTCs displayed on the scan tool? | -- | System OK |
