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P145A




DTC P1458-P145A

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 provides an overview of each diagnostic category.

DTC Descriptors
DTC P1458
- Evaporative Emission (EVAP) System Leak Detection Pump Pressure Sensor Performance

DTC P1459
- Evaporative Emission (EVAP) System Leak Detection Pump Pressure Sensor Circuit Low Voltage

DTC P145A
- Evaporative Emission (EVAP) System Leak Detection Pump Pressure Sensor Circuit High Voltage

Circuit/System Description

The EVAP leak detection pump assembly consists of three main components - a vacuum pump, a switching valve, and a pressure sensor. This DTC deals with the pressure sensor within the leak detection pump.

This diagnostic is executed when propulsion is active, engine ON or OFF, purge is not enabled, and the vent valve is closed or open. The diagnostic does not run when purge is enabled because it can influence the EVAP leak detection pump pressure sensor reading if there is any restriction in the fresh air plumbing.

This diagnostic is disabled when the Fuel Tank Pressure (FTP) Sensor Circuit Performance Diagnostic P0451 or the EVAP System Low Purge Flow Diagnostic P0497 is currently running.

The EVAP leak detection pump pressure sensor performs a correlation to barometric pressure (BARO). After a short delay period, the EVAP leak detection pump pressure sensor, absolute, reading is compared to the BARO based on the MAP sensor. Large deviations will increment the fail counter. When the fail count threshold is exceeded, then P1458 is set. There are two different threshold calibrations used in the comparison to the BARO. A smaller threshold is used when there has been a recent BARO update and then a larger threshold value is used when there has not been.

Conditions for Running the DTC
P1458

Note: 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.

Condition 1: Propulsion System Not Active
* The barometric pressure (BARO) is greater than 70 kPa, but less than 110 kPa (10.15-15.95 PSI).
* The fuel level is between 10% and 90%.
* The engine coolant temperature (ECT) is less than 40°C (104°F).
* The intake air temperature (IAT) is greater than 4°C (39°F), but less than 45°C (113°F).

Note: The 10 and 17 hours mentioned below do not apply if a code clear is performed. This test will run immediately after a code clear, if all other conditions are met.

* The battery voltage is greater than 10 volts.
* Vehicle speed is less than 1 MPH.

If any of these conditions occur this test is aborted.
* Key up during test
* Refueling request button pressed
* Service bay test active
* Device control exceeds 0.5 seconds
* 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, P0722, P0723, P1221, P1459, P145A, P2066, P2067, P2068, P2400, P2401, P2402, P2418, P2419, P2420, P2537, P2610, U0073, U0074, U0140, U182D are not present.
* P1458 or P145D not present when test failed this key on.
* P043E, P043F, P0443, P0451, P0458, P0459, P145A, P145C, P145D, P145E, P145F, P2421, P2422 and P2450 are not present.

Condition 2: Propulsion System Active and Engine On
* The barometric pressure (BARO) greater than 70 kPa, but less than 110 kPa.
* The outside air temperature (OAT) greater than 4°C (39°F), but less than 35°C (102°F).
* The engine is running.
* The run/crank voltage is greater than 11 volts.
* Purge is not enabled.

If any of these conditions occur this test is aborted.
* Refueling request button pressed
* Device control exceeds 0.5 seconds
* FTP correlation diagnostic P0451 is running
* Purge low flow diagnostic P0497 is running
* P0068, P0071, P0072, P0073, P0101, P0102, P0103, P0106, P0107, P0108, P010C, P010D, P0111, P0112, P0113, P0114, P0121, P0122, P0123, P012B, P012C, P012D, P0222, P0223, P0442, P0443, P0449, P0452, P0453, P0455, P0458, P0459, P0498, P0499, P0502, P0503, P0606, P0722, P0723, P16F3, P1104, P1221, P1458, P1459, P145A, P145D, P145E, P2100, P2101, P2102, P2103, P2400, P2401, P2402, P2418, P2419, P2420, P2422, P2450 are not present.

P1459 and P145A

Runs any time the ECM is awake and the propulsion is system active or not.

Conditions for Setting the DTC

P1458
* When the propulsion system is not active - If the difference between the EVAP system leak detection pump pressure sensor, absolute, reading and the BARO value from the MAP sensor is 3 kPa (0.44 PSI) for 14 s.
* When the propulsion system is active, and after a stabilization time of 10 s - When a recent BARO update has occurred within the last 0.1 km (0.06 mi), if the difference between the EVAP system leak detection pump pressure sensor, absolute, reading and the BARO value from the MAP sensor is 15 kPa (2.17 PSI).
* When a recent BARO update has not occurred within the last 0.1 km (0.06 mi) - If the difference between the EVAP system leak detection pump pressure sensor, absolute, reading and the BARO value from the MAP sensor is 20 kPa (2.9 PSI).

P1459

The ECM detects that the EVAP system leak detection pump pressure sensor signal is less than 0.7 V for greater than 8 s.

P145A

The ECM detects that the EVAP system leak detection pump pressure sensor signal is greater than 4.85 V for greater than 8 s.

Action Taken When the DTC Sets

DTCs P1458, P1459 and P145A are Type B DTCs.

Conditions for Clearing the DTC

DTCs P1458, P1459 and P145A are Type B DTCs.

Diagnostic Aids

* Compare MAP, BARO reading, scan tool reading with Service Mode active against the EVAP system leak detection pump sensor reading. A BARO standard reading is needed to determine which sensor is out of range.
* A normal BARO reading of the vehicle's geographic location will help to determine if a BARO sensor is way off its reading.
* Test for a plugged 5 micron in-line vent filter between the EVAP system leak detection pump and the fuel fill neck.

Reference Information
Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams
Description and Operation

Evaporative Emission Control System Description Evaporative Emission Control System Description

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 Control Module References for scan tool information

Circuit/System Verification

Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the Q63 EVAP system leak detection pump assembly.
2. Test for less than 5 ohm between the Q63 EVAP system leak detection pump assembly low reference circuit terminal 8 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. Service Mode active, test for 4.8-5.2 V between the 5 V reference circuit terminal 6 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 EVAP leak detection pump pressure sensor parameter is less than 1 kPa (0.15 PSI).

• If greater than the specified range, test the signal circuit terminal 7 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 signal circuit terminal 7 and the 5 V reference circuit terminal 6. Verify the scan tool EVAP leak detection pump pressure sensor parameter is greater than 127 kPa (18.42 PSI).

• 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.

6. If the circuits test normal, replace the Q63 EVAP system leak detection pump assembly.

Repair Instructions

* Clear DTCs.
* Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Evaporative Emission System Vacuum Leak Detection Pump Replacement Service and Repair
* Control Module References Control Module References for ECM replacement, setup, and programming

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