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B0158 CADILLAC

B0158 CADILLAC - Ambient Air Temperature Sensor Circuit

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Faulty Ambient Air Temperature Sensor
  • Ambient Air Temperature Sensor harness is open or shorted
  • Ambient Air Temperature Sensor circuit poor electrical connection
  • Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module

Tech notes

B0158 02: Ambient Air Temperature Sensor Circuit Short to Ground
B0158 05: Ambient Air Temperature Sensor Circuit High Voltage/Open

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

B0158 Cadillac Description

Air temperature sensors allow the Heating, Ventilation, and Air Conditioning (HVAC) Control Module to monitor the temperature of the discharge air in the HVAC ducts. The module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The module provides ground to the air temperature sensors through the low reference circuit. The HVAC control module monitors the voltage drops across the air temperature sensors and uses the inputs for automatic control calculations. When the duct air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the duct air temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The HVAC control module converts the voltage values to count values where 1 volt is approximately equal to 51 counts.
OBDII Code B0158 Cadillac - Ambient Air Temperature Sensor Circuit - AutoCodes.com

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