01-05 6.6 LB7 LLY Tech 2 Displaying minus 40 Degrees on ECT or IAT

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

The Engine Coolant Temperature or Intake Air Temperature sensor may read -40 degrees when monitored with Tech 2.

1. This condition is caused by a Tech 2 software concern
2. Currently there are no repairs for this Tech 2 software concern and replacing the ECM will not repair the condition.
3. The ECT and IAT data will return to normal after the ignition key is cycled to off or the engine is started.
4. This Tech 2 software concern will not cause P0116 or P0181 to set. When completing diagnosis for P0116 or P0181 the Tech 2 ECT or IAT data showing negative 40 degrees may lead to misdiagnosis. If there is a temperature sensor DTC set, check freeze frame data. If negative 40 degrees is not shown as the failure temperature, diagnose the DTC P0116 or P0181 as per SI information.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(01-05 CHEVROLET SILVERADO, GMC SIERRA C2, C3, K2, K3 WITH 6.6 LB7 ENGINE)

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