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OBD-II Trouble Shooting Got a code reader? Find out what your GM car's Check Engine light is trying to tell you (and then turn Check Engine light off).

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Old 10-27-2009, 01:13 AM   #1
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Default P0405


EGR position sensor low voltage

The powertrain control module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor circuit is open or shorted. If the PCM detects an excessively low EGR feedback signal voltage, the DTC will be set.

  • Symptoms
    System voltage is greater than 10 volts.
  • The PCM will illuminate the malfunction indicator lamp (MIL) during the second trip in which the diagnostic test has been run and failed.
  • The PCM will store conditions, which were present when the DTC set as Freeze Frame and Failure Records data.
  • If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.
  • EGR feedback is less than 0.14 volts at any time
  • The condition is present for more than 20 seconds.
  • A faulty connector at the PCM or the EGR valve – inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. Use a corresponding mating terminal to test for proper tension.
  • Inspect the wiring harness for damage. If the harness appears to be OK. Connect a digital multimeter (DMM) and check the circuit continuity while moving the connectors and the wiring harness related to the EGR valve. A change in the DMM display indicates the location of the malfuntion.
  • Check for 5V between the EGR pintle position sensor and ground. 5V is the signal voltage and must be present.
  • Check for an open in the 5 volt reference A circuit between the PCM and the EGR, if a problem is found repair. If no problem is found check the circuits related to the EGR valve for a faulty terminal connection at the PCM. If not problem is found, replace the PCM.
  • With ignition off, disconnect PCM and check for an open in the EGR pintle position circuit. If a problem is found, repair.
  • With ignition off, disconnect PCM and with a test lamp connected to B+. If the lamp lights, locate the short to ground in the EGR pintle position circuit. If it does not light, check for a short with the pintle position signal circuit in the sensor ground circuit.
If the EGR shows excessive heat, check for exhaust system blockage (possibly a plugged converter). If the exhaust system is restricted, repair the cause which might be an injector which us open due to stuck, grounded driver circuit or possibly faulty control module.
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