P0452
DTC P0451-P0453
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provide an overview of each diagnostic category.
DTC Descriptors
DTC P0451
- Fuel Tank Pressure (FTP) Sensor Performance
DTC P0452
- Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage
DTC P0453
- Fuel Tank Pressure (FTP) Sensor Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The fuel tank pressure (FTP) sensor measures the pressure or vacuum in the evaporative emission (EVAP) system. The engine control module (ECM) supplies a 5 V reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum.
The following tables illustrate relationship examples between the FTP sensor and the ON and OFF states, and the OPEN or CLOSED states of the EVAP components:
Conditions for Running the DTC
P0451 - Condition 1:
* DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0128, P012B, P012C, P012D, P0222, P0223, P0449, P0452, P0453, P0461, P0462, P0463, P0498, P0499, P0502, P0503, P06E4, P06E4, P0722, P0723, P1221, P1459, P145A, P2066, P2067, P2068, P2400, P2401, P2402, P2418, P2419, P2420, U0140, U182D, U0073, U0074, P2537 or P2610 is not set.
* DTC P1458 or P145D are not present when the test failed this ignition cycle.
* The barometric pressure (BARO) is between 70-110 kPa (10 -16 PSI).
* The fuel level is between 10-90 %.
* The engine coolant temperature (ECT) is less than 40°C (104°F).
* The intake air temperature (IAT) is between 4°-45°C (39°-113°F).
* The propulsion system is not active.
* The vehicle is OFF.
* The service bay test is not active.
* The refueling request button is not pressed.
* The battery voltage is greater than 10 V.
* The vehicle speed is less than 1.6 km/h (1 MPH).
* There are three possible time windows for this test to run. Up to that point and through this time period the propulsion system must not be active. These time windows are: 5.0, 7.0 or 9.5 hours.
* The DTC runs once per drive cycle and immediately after a code clear when the above conditions are met.
P0451 - Condition 2:
* DTCs P0068, P0071, P0072, P0073, P010C, P010D, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P012B, P012C, P012D, P0121, P0122, P0123, P0222, P0223, P0442, P0443, P0449, P0452, P0453, P0455, P0458, P0459, P0498, P0499, P0502, P0503, P0722, P0723, P0606, P1104, P1221, P145A, P145D, P145E, P1458, P1459, P16F3, P2100, P2101, P2102, P2103, P2400, P2401, P2402, P2418, P2419, P2420, P2422 or P2450 is not set.
* The barometric pressure (BARO) is between 70-110 kPa (10-16 PSI).
* The outside air temperature (OAT) is between 4°-35°C (39-102°F).
* The engine is running.
* The run/crank voltage is greater than 11 V.
* The EVAP Purge solenoid valve is not enabled.
* The refueling request button is not pressed
* The DTC runs once per drive cycle when the above conditions are met.
P0452 and P0453
* Vehicle ON or the engine is running.
* DTCs P0452 and P0453 run continually when the above conditions are met.
Conditions for Setting the DTC
P0451
The ECM detects the difference between the FTP sensor and the EVAP leak detection pump (ELDP) pressure is greater than 0.747 kPa (0.11 PSI) for greater than 5 s
P0452
The ECM detects the FTP sensor voltage is less than 0.15 V for greater than 8 s.
P0453
The ECM detects the FTP sensor voltage is greater than 4.85 V for greater than 8 s.
Action Taken When the DTC Sets
DTCs P0451, P0452 and P0453 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0451, P0452 and P0453 are Type B DTCs.
Diagnostic Aids
* A restriction in the EVAP canister or vent lines that keeps the FTP and ELDP sensor from comparing each others value.
* Since this is a sealed system there could be a pressure or vacuum existing in the system.
* A vent valve stuck closed will affect performance.
* A switching valve stuck in the vent position will affect performance.
* Ensure that the reference port on the FTP sensor is unobstructed.
* Scan tool output controls, snapshot, and the plot function can help detect erratic sensor operation.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation
Evaporative Emission Control System Description Description and Operation
Hybrid Modes of Operation Description Hybrid Modes of Operation Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Special Tools
GE-41413-A Evaporative Emissions System Tester
For equivalent regional tools, refer to Special Tools (Diagnostic Tools) Special Tools (Diagnostic Tools).
Circuit/System Verification
Note: The order of these steps is important. If not followed properly you will be bleeding off any pressure or vacuum in the system and not see any change in the ELDP sensor.
Note: Read the instructions for P0451 in their entirety before proceeding to understand what is being required.
Note: Ambient and vehicle component temperature must be above 0°C (32°F) to command the switching valve or vacuum pump. This prevents erroneous results and damage to the ELDP assembly.
P0451
1. Vehicle in Service Mode, whatever the FTP sensor parameter, pressure or vacuum, is showing on the scan tool, release it with the Venting command button under controls functions, EVAP Vent Solenoid Valve command. FTP sensor parameter should be 0.07 in. H2O, 0.01 kPa (0.00 PSI) after 5 s.
Note: There is a conversion button on the right hand side of the scan tool screen called Light Switch to toggle between kPa/Metric and PSI/English values.
2. Using the scan tool control functions, EVAP Test, command the ELDP pump on to get the FTP sensor parameter to -11.56 in. H2O, -2.88 kPa (-0.42 PSI) or greater. This may take several seconds.
Note: Use of any control function other than EVAP test will not create a vacuum in the system.
Note: Vacuum will decay exiting the EVAP test and going to step 3. This is normal. There should be sufficient vacuum left to perform steps 3 and 4.
3. Observe and note the ELDP and FTP sensor parameters with a scan tool. Note, reading one.
4. Perform the following steps in this order.
* Select scan tool Fuel Tank Pressure Sensor Test under control functions.
* Command the ELDP switching valve command to not venting by clicking the corresponding button.
* Wait for 3 seconds.
* Command the EVAP vent solenoid valve command ON by clicking the corresponding button.
Note: Wait for 15 s while observing the parameters then click the pause button on the scan tool to retain the parameters.
5. Observe and note the ELDP and FTP sensor parameters with a scan tool. Note, reading two. Press the Release Control button when the noted parameters are recorded.
Note: The subtraction results and FTP parameter should be negative since a vacuum was pulled on the system.
6. Subtract the ELDP reading 2 from ELDP reading 1. This value equals what the FTP sensor, reading two, should be (ELDP reading 2 - ELDP reading 1 = FTP reading 2). The FTP sensor should be within 3 in. H2O, 0.749 kPa (0.11 PSI) of the subtraction just performed.
• If not refer to diagnostics aids and perform circuit/system testing.
• If FTP sensor shows within 3 in. H2O, 0.749 kPa (0.11 PSI).
7. All OK.
P0452 and P0453
1. Request a refueling event. This opens the vent valve to bleed off any pressure or vacuum.
2. Remove the fuel cap.
3. Vehicle in Service Mode.
4. Observe the scan tool FTP sensor parameter. It should be 2.63 V at 0 kPa (0 PSI).
Circuit/System Testing
1. Vehicle OFF, disconnect the harness connector B150 fuel tank pressure sensor.
Note: Testing for steps 2-6 is performed on the ECM side of the harness connector.
2. Vehicle OFF, all systems OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the B150 fuel tank pressure sensor low reference circuit terminal 2 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.
3. Vehicle in Service Mode, test for 4.8-5.2 V between the B150 fuel tank pressure sensor 5 V reference circuit terminal 3 and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
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 sensor circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
5. Install a 3 A fused jumper wire between the B150 fuel tank pressure sensor signal circuit terminal 1 and the 5 V reference circuit terminal 3. Verify the scan tool FTP sensor 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.
Note: Testing for this step is performed on the EVAP assembly side of the harness connector.
6. Remove the EVAP assembly and test, inspect, and repair the items listed below. If all items test normal, replace the B150 fuel tank pressure sensor.
* Poor connection at the X350 harness connector
* Open or shorted 5 V reference circuit
* Open or shorted sensor signal circuit
* Open low reference circuit
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Fuel Tank Pressure Sensor Replacement Service and Repair
* Control Module References Programming and Relearning for ECM replacement, setup, and programming