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HOMESERVICE MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 11 (ENGINE CONTROL SYSTEM - 4.3L - DTC P0016 TO DTC P0138)DTC P0128CONDITIONS FOR CLEARING THE MIL/DTC
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2

Conditions for Clearing the MIL/DTC

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Conditions for Clearing the MIL/DTC
WARNING: This page is about a different variant/trim than selected.
  • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  • Clear the MIL and the DTC with a scan tool.
DTC P0128

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) 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
IMPORTANT: The cooling fans are commanded ON when certain engine coolant temperature (ECT) DTCs are set.
Is the cooling system coolant low?		 - Go to Draining and Filling Cooling System (Static Fill) or Draining and Filling Cooling System (Vac N Fill) in Engine Cooling Go to Step 3 
3 Test and verify the proper operation of the thermostat. Refer to Thermostat Diagnosis in Engine Cooling.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 4 
4
  1. Disconnect the ECT sensor.
  2. Inspect for the following conditions:
Did you find and correct the condition?		 - Go to Step 14  Go to Step 5 
5 Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 6 
6 Measure the resistance of the ECT sensor signal circuit between the sensor and the PCM with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance within the specified range?		 0-10 Ω Go to Step 7  Go to Step 10 
7 Measure the resistance of the ECT sensor low reference circuit between the sensor and the PCM with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance within the specified range?		 0-10 Ω Go to Step 8  Go to Step 11 
8
  1. Turn OFF the ignition.
  2. Remove the ECT sensor.
  3. Place the sensor on a work surface away from any heat source.
  4. Allow the sensor to reach the ambient air temperature for 30-60 minutes.
  5. Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer.
  6. Measure the resistance of the ECT sensor and record the value.
  7. Compare the resistance measurement of the ECT sensor to the ambient air temperature on the Temperature vs. Resistance table. Refer to Temperature vs Resistance .
Is the resistance measurement of the ECT sensor within the specified range?		 - Go to Step 9  Go to Step 12 
9 Install the ECT sensor.
Is the action complete?		 - Go to Step 13  -
10 Repair the high resistance in the ECT sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 14  -
11 Repair the high resistance in the ECT sensor low reference circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 14  -
12 Replace the ECT sensor. Refer to Engine Coolant Temperature (ECT) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 14  -
14
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 15 
15 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
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.