Body, generic

B0166 HVAC Discharge Air Temperature Sensor

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

The public J2012 lists do not contain B0166, and no make describes it as a discharge air sensor. Saab does use it, for the cabin rather than the outlet: in 9-3 climate control manuals from 2003 to 2012, B0166 05 marks the indoor or compartment temperature sensor as open or shorted to supply once the module input rises above 4.8 V, checked continuously with the ignition on; B0165 02 is the matching short to ground. Discharge or duct air sensors are NTC thermistors in the outlet ducts that let the module check what it actually delivers. GM's Global A system, per the 2011 Saab 9-5 manual, numbers them B0173, B0178, B0509 and B0514. A B0166 therefore needs the make's own definition.

Likely causes

Sensor open or signal shorted to supply (Saab 9-3 cabin sensor)
Sensor connector loose or left unplugged after dashboard work
On other makes, the outlet duct sensor itself failed

Symptoms

  • Automatic climate control misjudges cabin or outlet temperature and over- or undercorrects
  • Set temperature is not held steadily

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–250
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

discharge air temp sensorin vehicle temperature sensorhvac control module

Related codes

B0160B0250B0173

References: saabwisonline.com, saabwisonline.com, saabwisonline.com.