GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Allure 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P042E

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 provides an overview of each diagnostic category.

DTC Descriptor

DTC P042E: Exhaust Gas Recirculation (EGR) Closed Position Performance

Circuit Description

The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.

The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.

The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided by the control module through the EGR solenoid low control circuit. The driver has the ability to detect an electrical malfunction on the EGR solenoid control circuits.

When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.

The control module is able to determine that the EGR valve is still open when the control module is commanding the EGR valve closed

Conditions for Running the DTC
    • DTC P0641 or P0651 are not set.
    • The Ignition 1 Signal voltage parameter is more than 11 volts.
    • The EGR valve is commanded to 0 percent for 36 seconds after the EGR valve has been commanded to open more than 40 percent for 1 second.
    • The EGR flow test is not running.

Conditions for Setting the DTC
    • The EGR Position Sensor parameter is more than 5.5 percent of the 5-volt reference of the EGR Learned Minimum Position parameter when the Desired EGR Position parameter is commanded to 0 percent for 36 seconds.
    • The EGR Position Sensor parameter is more than 40 percent and is steady for 1 second after a test failure and before the next test will be run.
    • The above conditions are met 4 times.

Action Taken When the DTC Sets

DTC P042E is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P042E is a Type B DTC.

Diagnostic Aids

Inspect for excessive deposits on the EGR valve pintle or seat. Remove the EGR valve and inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.

Circuit/System Verification

Important: If DTC P0405, P0406, P0641, P0651 are also set , diagnose those DTCs first.

    • With the ignition ON and the engine OFF, command the EGR from 0-90 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter through the entire range.
    • Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

Circuit/System Testing

Important: You must complete the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Ignition OFF, disconnect the EGR valve harness connector.
  2. Ignition ON, the EGR Position parameter should display less than 1 percent.
    3. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  3. Install a 3A fused jumper wire between the signal circuit and the 5-volt reference circuit at the EGR harness connector. The EGR Position Sensor parameter should display more than 90 percent.
    4. ⇒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 ECM.
  4. Disconnect the control module and measure the resistance of the EGR high control circuit and the EGR low control circuit. Each circuit should measure less than 5 ohms.
    5. ⇒If the resistance is more than the specified range, test each circuit for an open/high resistance.
  5. If all circuits test normal, replace the EGR valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for control module replacement, programming, and setup
    •  Exhaust Gas Recirculation Valve Replacement