P166B

DTC P166B

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptor

DTC P166B
- Intake Air (IA) Heater Over Temperature

Diagnostic Fault Information






Circuit/System Description

The intake air heater (IAH) is located in the air inlet tube and is used to warm the incoming air to aid in starting the engine and for proper cylinder combustion. The glow plug control module (GPCM) will command the IAH on when the engine coolant temperature is below 40°C (104°F). Power to the IAH is supplied by the battery positive voltage circuit. The IAH is connected to the GPCM by the following circuits. If there is a fault on any of these circuits or a condition in the IAH a DTC will set.

* The IAH temperature signal circuit
* The IAH command 1 circuit
* The IAH command 2 circuit
* The IAH voltage signal circuit
* The IAH current signal circuit
* The IAH feedback signal circuit

Conditions for Running the DTC

* The IAH is commanded ON
* The engine is running for more than 40 seconds.

Conditions for Setting the DTC

The IAH temperature is more than 80°C (176°F) for more than 3 seconds.

Action Taken When the DTC Sets

DTC P166B is a type B DTC.

Conditions for Clearing the DTC

DTC P166B is a type B DTC.

Circuit/System Testing

Replace the intake air heater.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests