The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the evaporative emission (EVAP) system, and the outside air pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage goes below a calibrated value, this DTC sets.
The following table illustrates the relationship between the FTP sensor signal voltage and the EVAP system pressure/vacuum.
FTP Sensor Signal Voltage | Fuel Tank Pressure |
---|---|
High, Approximately 1.5 Volts or More | Negative Pressure/Vacuum |
Low, Approximately 1.5 Volts or Less | Positive Pressure |
This diagnostic procedure supports the following DTC:
DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage
• | The engine is running. |
• | DTC P452 runs continuously when the above condition is met. |
• | The FTP voltage is less than 0.1 volt. |
• | All conditions present for more than 25 seconds. |
• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Clear the MIL and the DTC with a scan tool. |
• | If DTC P0122 and P0530 are also set, a short to ground on the 5-volt reference circuit may exist. |
• | If DTC P0641 is set, diagnose that DTC first. |
• | To locate an intermittent problem, use the scan tool to monitor FTP sensor voltage with the ignition ON, the engine OFF. Wiggling wires while watching for a change in FTP sensor voltage may locate the area where an open or short to ground in the wiring could lie. |
• | The signal voltage with the fuel cap OFF should read between 1.30-1.70 volts, which represents atmospheric pressure, or 0 inches of vacuum. |
Step | Action | Values | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 | Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Is the Fuel Tank Pressure Sensor parameter less than the specified value? | 0.1 V | Go to Step 4 | Go to Step 3 | ||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||
4 |
Is the voltage within the specified value? | 4.8-5.2 V | Go to Step 6 | Go to Step 5 | ||||
5 | Disconnect the following components, while monitoring the DMM:
Is the DMM within the specified value when any of the components are disconnected? | 4.8-5.2 V | Go to Step 11 | Go to Step 7 | ||||
6 |
Is Fuel Tank Pressure Sensor parameter within the specified value? | 4.8-5.2 V | Go to Step 9 | Go to Step 8 | ||||
7 | Test the FTP 5-volt reference circuit for an open or for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 | ||||
8 | Test the FTP signal circuit for an open or for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 | ||||
9 | Test for an intermittent and for a poor connection at the FTP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 | ||||
10 | Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 | ||||
11 | Replace the component that affected the 5-volt reference circuit. Refer to Throttle Body Assembly Replacement or Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
12 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
13 | Replace the engine control module (ECM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 | ||||
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |