Circuit Description
The DTC P0450 Fuel Tank Pressure (FTP) Sensor Circuit diagnostic monitors the FTP sensor signal for a high or low voltage. The fuel tank pressure sensor responds to changes in the fuel tank pressure or vacuum. The fuel tank pressure sensor signal voltage to the powertrain control module (PCM) varies from more than 4 volts with pressure in the fuel tank, to a minimum of 0.6 volts with a high vacuum condition in the fuel tank.
Conditions for Running the DTC
| • | DTC P1450 and DTC P1451 is not set. |
| • | The barometric pressure (BARO) is more than 75 kPa. |
| • | The intake air temperature is between -14°C and +70°C (7°F-158°F). |
| • | The engine coolant temperature is between -8°C to +110°C (18°F-230°F). |
| • | The engine is running. |
Conditions for Setting the DTC
The FTP sensor voltage is less than 0.1 volts for 5 seconds.
OR:
The FTP sensor voltage is more than 5.0 volts for 5 seconds.
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
| • | MIL turns OFF after 3 consecutively passing trips without a fault present. |
| • | History DTC clears after 40 consecutive warm-up cycles without a fault. |
| • | Perform the scan tool Clear DTC Information function. |
Diagnostic Aids
Check for any of the following conditions:
| • | Plugged sensor air vent hole. Inspect the sensor and clean if necessary. |
| • | When DTCs P0122 and P0450 are set together, check for a short to ground in the 5 volt reference circuit. The 5 volt supply circuit for the TP sensor and the FTP sensor are shared internally in the PCM. |
| • | If a DTC P0450 is intermittent, driving the vehicle under the conditions outlined in the Inspection/Maintenance (I/M) section can verify whether the fault is present. Refer to Inspection/Maintenance Evaporative Emission System Set . |
| • | An intermittent malfunction may be caused by a fault in the fuel tank pressure sensor circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions . |
If a DTC P0450 is intermittent, driving the vehicle under the following conditions may verify whether or not the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P0450 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0450 appears in the Not Ran Since Code Cleared list, the DTC P0450 diagnostic has not yet run. When the DTC P0450 does not appear in the Not Ran Since Code Cleared list, the DTC P0450 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0450 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.
If the DTC P0450 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.
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The Diagnostic System Check-Engine Controls 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.
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The fuel tank pressure sensor reading indicated on the scan tool will vary with the surrounding barometric pressure.
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The FTP sensor voltage will vary with the surrounding barometric pressure.
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This step verifies that the fuel tank pressure sensor is able to react to EVAP system pressure changes.
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This step checks the operation of the fuel tank pressure control valve.
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This step determines whether or not the malfunction that caused DTC P0450 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 P0450 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P0450 appears in the Not Ran Since Code Cleared list, the DTC P0450 diagnostic has not yet run. When DTC P0450 does not appear in the Not Ran Since Code Cleared list, the DTC P0450 diagnostic has run. If the MIL is NOT illuminated and there is no Pending DTC Status in DTC Information, the DTC P0450 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. 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 |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | ||
Is the pressure within the specified range? | 0.0-0.9 mm Hg (0.0-0.5 in. H2O) | Go to Step 11 | Go to Step 3 | |
3 |
Was any problem found? | -- | Go to Step 13 | Go to Step 4 |
4 |
Does the voltage equal the specified value? | 5.0 V | Go to Step 6 | Go to Step 5 |
5 |
Was a repair necessary? | -- | Go to Step 18 | Go to Step 14 |
6 | Probe the terminal 2 of the FTP sensor connector on the harness side using a test lamp connected to B+. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 7 |
7 |
Was a repair necessary? | -- | Go to Step 18 | Go to Step 14 |
Is the voltage within the specified range? | 2.5 - 2.7 V | Go to Step 9 | Go to Step 15 | |
Apply a small amount of vacuum to the FTP sensor while observing the DMM. Does the voltage decrease when the vacuum is applied? | -- | Go to Step 10 | Go to Step 16 | |
10 |
Was a repair necessary? | -- | Go to Step 18 | Go to Step 14 |
|
Caution: Do not breathe the air through the EVAP component tubes or hoses. The fuel vapors inside the EVAP components may cause personal injury.
Important: There will be some resistance, but air should flow steadily. Does air flow through the valve to the tank port side? | -- | Go to Step 12 | Go to Step 17 | |
12 |
Important: The FTP control valve allows vapor to flow from fuel tank to the canister when the fuel tank pressure is greater than canister pressure by more than 3.5 kPa (0.5 psi).
Does the FTP control valve pass this test? | -- | Go to Diagnostic Aids | Go to Step 17 |
13 | Clean the sensor orifice. Is the action complete? | -- | Go to Step 18 | -- |
14 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 18 | -- |
15 |
Was a repair necessary? | -- | Go to Step 18 | Go to Step 16 |
16 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | Go to Step 18 | -- |
17 | Replace the FTP control valve. Refer to Fuel Tank Pressure Control Valve Replacement . Is the action complete? | -- | Go to Step 18 | -- |
Does the DTC run and pass? | -- | Go to Step 19 | Go to Step 2 | |
19 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
