For 1990-2009 cars
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The PCM monitors the fuel tank pressure sensor signal to detect vacuum decay and excess vacuum during the enhanced EVAP diagnostic. The fuel tank pressure sensor measures the difference between the air pressure (or vacuum) in the tank and the outside air pressure. The PCM applies a 5.0 volt reference and ground to the sensor. The sensor will return a signal voltage between 0.1 and 4.9 volts. If the PCM detects a fuel tank pressure sensor signal that is excessively low, DTC P0452 will set.

### Conditions for Running the DTC

• | System voltage between 10.0 and 18.0 volts

• | The ignition is on.

### Conditions for Setting the DTC

• | The fuel tank pressure sensor signal is less than 0.5 volts.

• | The conditions is present for 5 second.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using a scan tool.

### Diagnostic Aids

Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.

Check for the following condition(s):

• | Poor connection at the PCM or Fuel Tank Pressure Sensor.

| Inspect harness connectors for backed out terminals, improper mating broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

• | Damaged harness.

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

### Test Description

Numbers below refer to the step numbers on the Diagnostic Table:

1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

#### 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 the Powertrain On Board Diagnostic (OBD) System Check
2 | Important: If a 5 volt reference DTC sets, diagnosis that DTC first.

1. Turn ON the ignition, with the engine OFF.
2. With a scan tool, observe the fuel tank pressure parameter.

Does the scan tool indicate fuel tank pressure less than the specified value?

0.3 V

Go to Step 4

Go to Step 3

3 | Important: Continue the diagnosis at step 4 if you were sent here from one of the EVAP diagnostic tables.

1. With a scan tool, capture Fail Records data and clear the DTCs.
2. Operate the vehicle within fail records conditions.
3. Use a scan tool to monitor specific DTC info for DTC P0452.

Does the scan tool indicate DTC P0452 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Disconnect the fuel tank pressure sensor electrical connector.
2. Connect a 3 amp fused jumper between the fuel tank pressure signal circuit and the 5 volt reference B circuit at the fuel tank pressure sensor harness connector.
3. Use a scan tool to observe fuel tank pressure parameter.

Does the scan tool indicate fuel tank pressure near the specified value?

5.0 V

Go to Step 8

Go to Step 5

5 | With a DMM, measure voltage between the 5 volt reference B circuit and the sensor ground circuit at the fuel tank pressure sensor harness connector. Does the DMM indicate voltage near the specified value? | 5.0 V | Go to Step 9 | Go to Step 6
6 |

1. Turn OFF the ignition.
2. Test the 5 volt reference B circuit for a poor terminal connection at the PCM. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 7

7 | Test the 5 volt reference B circuit between the fuel tank pressure sensor and the PCM for an open, short to ground, or short to the sensor ground circuit. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

8 | Test for poor terminal connections at the fuel tank pressure sensor connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11
9 |

1. Turn OFF the ignition.
2. Test the fuel tank pressure sensor signal circuit for a poor terminal connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10 | Test the fuel tank pressure signal circuit between the fuel tank pressure sensor connector and the PCM for an open, short to ground, or short to the sensor ground circuit. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | --
12 | Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 13 | --
13 |

1. With a scan tool, clear the DTCs.
2. Start the engine, operate the vehicle within the conditions for setting the DTC.

Does the scan tool indicate that this diagnostic has ran and passed?

--

System Ok

Go to Step 2