B3A29
Serious Severity (Level 4)Active Aerodynamic Feature Control Module B Power Mode Circuit Low Voltage
B3A29 usually means active Aerodynamic Feature Control Module B Power Mode Circuit Low Voltage.
Can you still drive with B3A29?
⚠️Limited driving — get to a repair shop within 1–2 days. Avoid long trips and highway speeds.
Typical repair cost: $150 – $2000
Severity Level 4 — Serious
This code indicates a serious issue that can cause noticeable driveability problems and potential engine damage if not addressed. The vehicle should be taken to a mechanic as soon as possible. Extended driving is not recommended.
Common Symptoms
- Engine control reading zero or abnormally low
- Check Engine Light illuminated
- Diagnostic trouble code (DTC) stored in module memory
- Fault may be intermittent — code may clear itself and reappear
- Reduced vehicle functionality related to the engine/body control module
Possible Causes
- Failed control module — internal resistance has increased, outputting a signal lower than specification
- Damaged wiring or corroded connector in the engine/body control module circuit introducing high resistance
- Short to ground in the engine/body control module signal wire — wire chafed through, signal voltage pulled low
- Loose or oxidized ground connection for the control module — clean the ground and retest before replacing parts
- Low system voltage (weak battery or failing alternator) causing sensor reference voltage to sag
Common Fixes
- Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($4-147 at shop, free at auto parts store for basic scan)
- Visually inspect the engine/body control module wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $139 diagnostic fee at shop)
- Test control module with a multimeter at the connector — compare readings to factory service manual specs. If out of spec, replace control module ($150-2000)
- Check the reference voltage supply to control module — should be steady 5V (or 12V) — if low, trace back to PCM/BCM voltage regulator ($136-354 if module repair needed)
- Perform a voltage drop test on the ground side of the engine/body control module circuit — more than 0.1V drop means a bad ground that must be cleaned/repaired ($98-254 at shop)
Estimated Repair Cost
These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.
Frequently Asked Questions
What does B3A29 mean?
B3A29 stands for "Active Aerodynamic Feature Control Module B Power Mode Circuit Low Voltage". B3A29 usually means active Aerodynamic Feature Control Module B Power Mode Circuit Low Voltage.
Can you drive with B3A29?
Limited driving — get to a repair shop within 1–2 days. Avoid long trips and highway speeds.
How much does it cost to fix B3A29?
Repair costs for B3A29 typically range from $150 to $2000, depending on your vehicle make, model, and local labor rates. Common fixes include: Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($4-147 at shop, free at auto parts store for basic scan); Visually inspect the engine/body control module wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $139 diagnostic fee at shop); Test control module with a multimeter at the connector — compare readings to factory service manual specs. If out of spec, replace control module ($150-2000).
Will B3A29 clear itself?
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