B0429: Auxiliary Air Temperature Actuator Range/Performance
2 vehicles · 2 makes · $60-$500 repair
Most Reported On
B0429 is an OBD-II diagnostic trouble code meaning “Auxiliary Air Temperature Actuator Range/Performance.” A body code used by General Motors (Chevrolet, GMC, Cadillac) for the auxiliary — typically rear — air temperature blend actuator; some references also render it as rear temperature control circuit out of range. The auxiliary HVAC actuators are 5-wire bi-directional motors with a built-in feedback potentiometer using a low reference, 5-volt reference, position signal, and two control circuits. As the actuator shaft rotates, the position signal varies between 0 and 5 volts, which the module converts to counts (1 volt equals 51 counts, so 0-255); B0429 sets when the reported position falls outside the expected range. The symptom is rear or auxiliary-zone air that will not change temperature, stays stuck hot or cold, or a clicking noise behind the trim. This is a comfort fault, not a drivability or safety issue. This code is most commonly reported on 2007-2014 GMC Yukon, and 2011-2019 Chevrolet Cruze, with repair costs ranging from $60 to $500.
Common Causes
Typical Repair Cost
Based on 2 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
This is a body code. A basic engine-code reader will not show it — you need a scanner that reads body modules. These read B0429.
One caveat that applies to every scanner: only powertrain codes are standardised across manufacturers. Body, chassis and network coverage is "enhanced" diagnostics, and how deep it goes varies by make and model year — check your specific vehicle against the tool's coverage list before buying.
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level tablet with all-system coverage and bi-directional control, so you can command a module rather than only read it.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
What you can do yourself, and what needs a shop
Reading the code, clearing it, and watching whether it returns is a driveway job with the right scanner. These steps are not:
- Module programming or software updates — needs the manufacturer software or a J2534 pass-through with a paid subscription.
- Replacing a control module — most are VIN-programmed and immobilizer-registered, so a new one does nothing until it is coded to your car.
- Airbag/SRS component work — a stored fault can deploy a live device.
If the vehicle is still under warranty, check for an open recall or technical service bulletin before buying anything — the repair may already be covered.
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FAQ
What does B0429 mean?
B0429 stands for "Auxiliary Air Temperature Actuator Range/Performance." A body code used by General Motors (Chevrolet, GMC, Cadillac) for the auxiliary — typically rear — air temperature blend actuator; some references also render it as rear temperature control circuit out of range. The auxiliary HVAC actuators are 5-wire bi-directional motors with a built-in feedback potentiometer using a low reference, 5-volt reference, position signal, and two control circuits. As the actuator shaft rotates, the position signal varies between 0 and 5 volts, which the module converts to counts (1 volt equals 51 counts, so 0-255); B0429 sets when the reported position falls outside the expected range. The symptom is rear or auxiliary-zone air that will not change temperature, stays stuck hot or cold, or a clicking noise behind the trim. This is a comfort fault, not a drivability or safety issue.
What are the most common causes of B0429?
The most common causes of B0429 are: Failed auxiliary/rear air temperature actuator (stripped gears or a failed feedback potentiometer are common), Actuator harness open or shorted, Poor electrical connection at the actuator — corroded or loose connector, Blend door binding or broken off its pivot, Failed HVAC control module, Actuator not recalibrated after battery disconnect or replacement. The specific cause varies by vehicle.
How much does it cost to fix B0429?
Repair costs for B0429 range from $60 to $500, depending on the vehicle and root cause.
Which vehicles are affected by B0429?
Au7o has documented B0429 across 2 vehicle models from 2 manufacturers: Chevrolet, GMC.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.