Ambient Air Temperature Sensor Circuit
|
Overview
CODE | REASON | EFFECT |
Fault Code: 256 PID: P171 SPN: 171 FMI: 4/4 LAMP: Yellow SRT: |
Low voltage detected at the ambient air temperature circuit. |
No effect on engine performance. The idle shutdown ambient air temperature override feature will use the intake manifold air temperature sensor value to determine idle shutdown and availability of override (automotive only). |
![]() Ambient Air Temperature Sensor Circuit
|
Circuit Description
The ambient air temperature sensor is used by the electronic control module (ECM) to monitor the temperature of the ambient air. The ambient air temperature signal is used by the ECM for the idle shutdown ambient air temperature override and ICON™ features.
Component Location
The ambient air temperature sensor location is OEM dependent. Use the OEM troubleshooting and repair manual.
Shop Talk
The resistance of the sensor varies with the temperature. The reading you observe should compare to this table:
Temperature (°C)
|
Temperature [°F]
|
Resistance (ohms)
|
0
|
32
|
30k to 36k
|
25
|
77
|
9k to 11k
|
50
|
122
|
3k to 4k
|
75
|
167
|
1350 to 1500
|
100
|
212
|
600 to 675
|
Refer to Troubleshooting Fault Code t05-256.