For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provide an overview of each diagnostic category.

### DTC Descriptors

DTC P0451 00: Fuel Tank Pressure Sensor Performance
DTC P0452 00: Fuel Tank Pressure Sensor Circuit Low Voltage
DTC P0453 00: Fuel Tank Pressure Sensor Circuit High Voltage
DTC P0454 00: Fuel Tank Pressure Sensor Intermittent

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Fuel Tank Pressure Sensor 5-Volt Reference | P0107 00, P0452 00, P0532 00, P0641 00 | P0451 00 | P0452 00 | P0453 00, P0641 00 | --
Fuel Tank Pressure Sensor Signal | P0452 00 | P0451 00 | P0452 00 | P0453 00 | P0451 00, P0454 00
Fuel Tank Pressure Sensor Low Reference | -- | P0446 00, P0451 00 | P0446 00 | -- | --

### Typical Scan Tool Data

#### Fuel Tank Pressure Sensor Voltage

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Ignition ON, Engine OFF Parameter Normal Range: 1.3-1.7 V
Fuel Tank Pressure Sensor 5-Volt Reference | 0 V | 0-1.5 V | 5 V
Fuel Tank Pressure Sensor Signal | 0 V | 0 V | 5 V
Fuel Tank Pressure Sensor Low Reference | -- | 4.5 V | --

### Circuit/System Description

The fuel tank pressure sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The engine control module (ECM) supplies a 5-volt reference and a low reference circuit to the fuel tank pressure sensor. The fuel tank pressure sensor signal voltage varies depending on EVAP system pressure or vacuum. The ECM also uses this fuel tank pressure sensor signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442 00. Before using this signal as an atmospheric reference it must first be re-zeroed.

### Conditions for Running the DTC

#### P0451 00

• | DTCs P0452 00, P0453 00, P0642 00, P0643 00 are not set.

• | The engine has been running for more than 10 s.

• | The fuel tank pressure sensor signal is between 0.2-4.9 V.

• | The vehicle speed reached once during drive cycle of 20 km/h (14.2 mph).

• | The evaporative emission (EVAP) system has reached full purge and no purge once during drive cycle.

• | The EVAP system is purging.

• | DTC P0451 00 runs continuously when the above conditions have been met.

#### P0452 00 and P0453 00

• | DTCs P0642 00 and P0643 00 are not set.

• | The average fuel level is between 6-40 L (0-10 gal).

• | DTCs P0452 00 and P0453 00 run continuously when the ignition is ON.

#### P0454 00

• | DTCs P000A 00, P000B 00, P0010 00, P0013 00, P0016 00, P0017 00, P0030 00, P0031 00, P0032 00, P011 001, P0112 00, P0113 00, P0114 00, P0117 00, P0118 00, P0119 00, P0121 00, P0122 00, P0123 00, P0131 00, P0132 00, P0133 00, P0134 00, P0135 00, P0171 00, P0172 00, P0201 00, P0202 00, P0203 00, P0204 00, P0221 00, P0222 00, P0223 00, P0261 00, P0262 00, P0264 00, P0265 00, P0267 00, P0268 00, P0270 00, P0271 00, P0300 00, P0301 00, P0302 00, P0303 00, P0304 00, P0335 00, P0336 00, P0340 00, P0341 00, P0365 00, P0366 00, P0442 00, P0443 00, P0446 00, P0451 00, P0452 00, P0453 00, P0454 00, P0455 00, P0456 00, P0458 00, P0459 00, P0496 00, P0498 00, P0499 00, P0500 00, P0501 00, P0506 00, P0507 00, P0562 00, P0563 00, P0601 00, P0602 00, P0603 00, P0604 00, P0605 00, P0606 00, P0607 00, P061A 00, P0642 00, P0643 00, P2088 00, P2089 00, P2090 00, P2091 00, P2100 00, P2101 00, P2119 00, P2176 00, P2297 00, P2301 00, P2304 00, P2307 00, P2310 00, and P2A00 00 are not set.

• | The ignition is ON.

• | The barometric pressure (BARO) is more than 75 kPa (11 PSI).

• | The engine coolant temperature (ECT) sensor is less than 110°C (230°F).

• | The engine is idling.

• | The vehicle speed is 0 km/h (0 mph).

• | The fuel level is between 6-40 L (2-10 gal).

• | The fuel tank pressure sensor is between -3 kPa and +1 kPa (-0.4 PSI and +0.1 PSI).

• | The intake air temperature (IAT) is between -8.25°C and +70°C (+17°F and +158°F).

• | The battery voltage is more than 10 V.

• | The engine is operating in closed loop fuel control.

• | DTC P045 004 runs once per drive cycle when the above conditions have been met.

### Conditions for Setting the DTC

#### P0451 00

The maximum minus the minimum fuel tank pressure sensor signal voltage is less than 0.039 V for 5 s.

#### P0452 00

The fuel tank pressure sensor voltage is less than 0.1 V for more than 1 s.

#### P0453 00

The fuel tank pressure sensor voltage is more than 4.9 V for more than 1 s.

#### P0454 00

The maximum minus the minimum fuel tank pressure is more than 0.1 kPa (0.02 PSI) for 5 s.

### Action Taken When the DTC Sets

DTCs P045 001, P0452 00, P0453 00, and P0454 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0451 00, P0452 00, P0453 00, and P045 004 are Type B DTCs

### Diagnostic Aids

• | A restriction in the EVAP canister or vent lines may prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot bleed off pressure fast enough, the re-zero procedure may not complete successfully, which may cause this code to set.

• | Ensure that the reference port on the fuel tank pressure sensor is unobstructed.

• | Scan tool output controls, snapshot, and the plot function can help detect erratic sensor operation. To observe the fuel tank pressure sensor signal under vacuum conditions, use the quick snapshot and the EVAP purge/seal function to capture data while commanding purge to 20%. Then plot the data to look for erratic sensor operation. A similar test can be done for the pressure side of the sensor range by applying pressure with EN-41413-200 Evaporative Emissions System Tester (EEST) while taking a snapshot with the scan tool.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

EN-41413-200 Evaporative Emissions System Tester (EEST)

For equivalent regional tools, refer to Special Tools.

### Circuit/System Verification

1. Remove the fuel cap.
2. Ignition ON, engine OFF.
3. Observe the B150 Fuel Tank Pressure (FTP) Sensor parameter with a scan tool.
4. The FTP Sensor parameter should be 1.3-1.7 V.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B150 Fuel Tank Pressure (FTP) Sensor.
2. Ignition OFF, ensure that the ECM completely powers down and test for less than 5 Ω between the B150 Fuel Tank Pressure (FTP) Sensor low reference circuit terminal A and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, test for 4.8-5.2 V between the B150 Fuel Tank Pressure (FTP) Sensor 5-volt reference circuit terminal C and ground.

⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Verify the scan tool FTP sensor parameter is less than 0.2 V.

⇒ | If greater than the specified range, test the B150 Fuel Tank Pressure (FTP) Sensor signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Install a 3A fused jumper wire at the B150 Fuel Tank Pressure (FTP) Sensor signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool FTP sensor voltage parameter is greater than 4.7 V.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

6. If all circuits test normal, replace the B150 Fuel Tank Pressure (FTP) Sensor.

### Repair Instructions

• | For DTC P0452 00 or P0453 00, perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | For DTC P0451 00 or P0454 00, clear DTCs with a scan tool.

• | LINK (Fuel Tank Pressure (FTP) Sensor Replacement)

• | Control Module References for ECM replacement, setup, and programming