Body, generic

B0233 Air Flow Control Circuit

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modeNo

Public J2012 listings leave B0233 out, yet GM assigns it in its Global A climate control for the air distribution (mode) actuator. On 2011 Saab 9-5 and 9-4X cars that actuator is a stepper motor: the HVAC module feeds it a 12 V reference and switches its four coils to ground in pulses. B0233 01 means one of its control lines is shorted to voltage, B0233 06 that a line is open or low. The module tests the outputs only as the motor starts a move, not during travel or at the target. GM bulletin PIT5383 names B0233 among HVAC codes of 2015 models cured by reprogramming the K33 module. The rear distribution actuator reports B3531 instead. With the front actuator out, air keeps coming from the outlets last selected.

Likely causes

Mode stepper actuator failed internally, e.g. a burnt coil or worn gear

One of the four control lines or the 12 V reference chafed, open or shorted behind the dash

HVAC module software fault on affected GM models, fixed by reprogramming

Symptoms

Air comes from the wrong outlets and the selected distribution is ignored
Windscreen cannot be demisted because air will not switch to defrost

Repair estimate

DifficultyMediumDIY possible

Parts and labour€60–450

Time0.5–3 h

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

Parts involved

mode door actuatorhvac control module

Related codes

B0268 B0150 B0170

References: saabwisonline.com, saabwisonline.com, static.nhtsa.gov, motor.com.