GM Service Manual Online
For 1990-2009 cars only

System Description

The diagnostic strategy for the evaporative emission (EVAP) system uses a vacuum pump to test for system leaks, after the engine is OFF. A unique fuel tank, EVAP canister, and EVAP vacuum leak pump work together to provide enhanced system diagnosis. The vacuum leak pump, the fuel tank pressure (FTP) sensor and the EVAP canister vent valve are all integral parts of one assembly. The assembly is attached directly to the EVAP canister, located near the fuel tank.

After the vehicle has sat with the engine OFF for about 5 hours, a comprehensive diagnostic is enabled with no operator input necessary. The complete test can take up to 15 minutes to run, with leak detection comprising the largest portion of the test. For more detailed information on the EVAP system components and diagnostic theory, refer to Evaporative Emission Control System Description .

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P043E Evaporative Emission (EVAP) System Reference Orifice Flow Insufficient

Conditions for Running the DTC

    • DTCs P0110, P0112, P0113, P0115, P0117, P0118, P0441, P0450, P0451, P0452, P0453, P2610 are not set.
    • Five hours have elapsed after the engine was turned OFF.
    • Atmospheric pressure is between 70-110 kPa.
    • Battery voltage is more than 10.5 volts.
    • Engine coolant temperature is between 4-35°C (40-95°F).
    • Intake air temperature is between 4-35°C (40-95°F).
    • The ignition remains OFF for the duration of the test.
    • DTC P043E runs once per drive cycle when the above conditions are met.

Conditions for Setting the DTC

The powertrain control module (PCM) has determined the reference orifice of the EVAP vacuum leak detection pump is blocked or restricted.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
    • A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
    • A DTC can be cleared by using the scan tool Clear Information function.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. In order to correctly identify the malfunction, DTC P2401, P2402, and P2419 must be diagnosed before DTC P043E or P043F.

  2. This step uses the EVAP Service Bay test in order to verify the correct operation of the EVAP vent solenoid, the EVAP purge solenoid, and the EVAP vacuum leak pump. Using the Service Bay test also tests for leaks by sealing the system and monitoring the FTP sensor.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Inspect for additional evaporative emission (EVAP) system DTCs.

    • If there are EVAP system DTCs other than P043E or P043F diagnose those DTCs first.
    • Review the Freeze Frame/Failure Record and diagnose the DTC captured in the Freeze Frame/Failure Record first.

Are any other EVAP system DTCs set?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3

  1. Test for an intermittent and for a poor electrical connection at the EVAP vacuum leak pump. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
  2. Repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4

Replace the EVAP vacuum leak pump assembly. Refer to Evaporative Emission System Vacuum Leak Pump Replacement .

Did you complete the replacement?

Go to Step 5

--

5

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Perform the EVAP service bay test with the scan tool. Refer to EVAP Service Bay Test in Service Bay Test .

Did you complete the EVAP Service Bay Test?

Go to Step 6

--

6

  1. Check for any EVAP DTCs in Last Test Failed.
  2. Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK