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Home >> Pontiac >> 2008 >> G8 GT >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 6.0L - DTC P0016 To DTC P0335 >> DTC P0128 >> Circuit/System Verification
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Circuit/System Verification

  1. Ignition OFF, inspect the cooling system surge tank for proper coolant level. Refer to Cooling System Leak Testing and Cooling System Draining and Filling .
  2. Ignition OFF for 8 hours or greater.
  3. Ignition ON, observe the scan tool IAT Sensor and ECT Sensor parameters. The ECT, IAT, and ambient temperatures should be within 6°C (11°F) of each other.
  4. Use the scan tool to verify the proper operation of the engine cooling system fans.
    5. NOTE: A critical analysis of the operation of the thermostat is necessary, to properly diagnose these DTCs.
  5. Verify the proper heat range, and the operation of the thermostat. Refer to Thermostat Diagnosis .
  6. 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.
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