LEMON Manuals: Even more car manuals for everyone
Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 151 (Engine Control System - 3.8L - DTC P0451 To DTC P2120) >> DTC P0641 or P0651 >> Circuit/System Testing >> P0641

Circuit/System Testing: P0641

WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
  1. With the ignition OFF, disconnect the harness connector at the MAP sensor.
  2. With the ignition ON, measure for 4.8-5.2 volts between the MAP sensor 5-volt reference circuit and ground.
  3. Command the EGR valve to 100 percent while monitoring the MAP sensor 5-volt reference circuit with a DMM.
  4. With the ignition OFF, disconnect the harness connector at the EGR valve.
  5. With the ignition ON, measure EGR valve 5-volt reference circuit.
    • If within 4.8-5.2 volts, replace the EGR valve.
    • If over 5.2 volts, check for unexpected voltage at each 5-volt reference circuit or the signal circuit for each component associated with the 5-volt reference.
    • If under 4.8 volts, check for a short to ground or low reference circuit at each 5-volt reference circuit.
  6. With the ignition ON, use a scan tool to observe the voltage parameter for each component associated with the 5-volt reference circuit while disconnecting each component one at a time.
    • If the data parameters change with any component being disconnected, replace the component.
  7. If all circuits tested are OK, replace the control module.
scientia non olet · About LEMON Manuals