For 1990-2009 cars
Engine Controls Components
Engine Data Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The fuel tank pressure sensor is used in order to detect a vacuum decay or an excessive vacuum during the EVAP diagnostic routine. The sensor responds to the changes in the fuel tank pressure or vacuum. The signal voltage to the Powertrain Control Module (PCM) varies from a minimum of about 0.2 volts with pressure in the fuel tank to more than 4.0 volts with a high vacuum in the fuel tank.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

The fuel tank pressure sensor voltage is less than 0.1 volt for more than 25 seconds.

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will illuminate.

• | The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information.

• | A history DTC stores.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs without a fault.

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

• | Use a scan tool to clear the DTCs.

### Diagnostic Aids

Check for the following conditions:

• | Inspect the PCM harness electrical connectors for the following conditions:

- | Any incorrect mating

- | Any broken locks

- | Any incorrectly formed terminals or damaged terminals

• | Inspect the wiring harness for damage. If the harness appears to be OK, observe the Fuel Tank Pressure display on the scan tool while moving the electrical connectors and the wiring harnesses related to the sensor. A change in the display will indicate the location of the malfunction.

Refer to Evaporative Emission System Cleaning before starting repairs.

### Test Description

1. A normal fuel tank pressure sensor voltage output with no pressure or vacuum on the fuel system should be between 1.3 and 1.7 volts.

2. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

#### DTC P0452 - Fuel Tank Pressure Sensor Circuit Low Voltage

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. Start the engine and idle the engine.
2. With the scan tool, observe the fuel tank pressure.

Is the pressure more than or equal to the specified value?

0.2 V

Go to Step 3

Go to Step 4

3 | Operate the vehicle within the Freeze Frame conditions and the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | -- | Go to Step 4 | Go to Diagnostic Aids
4 |

1. Turn off the ignition.
2. Disconnect the fuel tank pressure sensor.
3. Turn on the ignition, leaving the engine off.
4. With a DMM in order to measure the voltage between the following circuits at the sensor connector:

• | The 5 volt reference circuit

• | The sensor ground

Does the voltage measure equal the specified value?

5.0 V

Go to Step 7

Go to Step 5

5 |

1. Inspect the 5 volt reference circuit for a poor connection at the PCM.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 6

6 | Important:: The PCM uses a single 5 volt power supply to all the engine control components. If one component shorts the 5 volt reference circuit to ground, the other 5 volt reference circuits will also have a low voltage.

1. Test the 5 volt reference circuit of the fuel tank pressure sensor for the following conditions:

• | An open

• | A short to ground

2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

7 |

1. Turn off the ignition.
2. Disconnect the fuel tank vapor line at the EVAP canister.
3. Install jumper wires between the sensor and the harness connector on the following circuits:

• | The 5 volt reference circuit

• | The sensor ground

4. Turn on the ignition, leaving the engine off.
5. With a DMM measure the sensor signal voltage at the sensor.

Is the voltage within the specified range?

1.3-1.7 V

Go to Step 8

Go to Step 10

8 |

1. Inspect the sensor signal circuit for poor connections.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

9 |

1. Test the sensor signal circuit for following conditions:

• | An open circuit

• | A short to ground

2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the repair? | -- | Go to Step 12 | --
11 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the repair? | -- | Go to Step 12 | --
12 |

1. Reconnect the vapor line from the fuel tank to the EVAP canister.
2. Use a scan tool to clear the DTCs.
3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK