What Does B2429 Mean?
This code indicates that the Body Control Module (BCM) has detected an abnormal voltage reading from the A/C Post Heater Sensor #2 circuit that is lower than expected, indicating a short circuit to ground. This sensor monitors the temperature of air after it passes through a secondary heater element in the HVAC system, typically used in climate control systems to ensure proper cabin temperature regulation. The short to ground condition means current is flowing directly to chassis ground rather than returning through the normal circuit path.
Common Causes
45%
Damaged or chafed wiring harness causing the sensor signal wire to contact ground or metal body components
30%
Failed A/C Post Heater Sensor #2 with internal short circuit to ground
15%
Corroded or moisture-damaged connector pins creating a ground path at the sensor or BCM connection points
10%
BCM internal fault causing incorrect ground detection on the sensor circuit
Diagnostic Steps
1
Step 1: Perform a visual inspection of the A/C Post Heater Sensor #2 and its wiring harness from the sensor to the BCM, checking for obvious damage, chafing, pinch points, or water intrusion. Pay special attention to areas where the harness passes through firewalls, near sharp edges, or around moving components.
2
Step 2: Disconnect the A/C Post Heater Sensor #2 connector and measure resistance between the sensor signal pin and ground using a digital multimeter. A reading of less than 10k ohms indicates a short to ground in the sensor itself. Compare to manufacturer specifications for sensor resistance at ambient temperature.
3
Step 3: With the sensor disconnected, measure resistance between the signal wire terminal in the vehicle harness connector and chassis ground. A reading of less than 10k ohms confirms a short to ground in the wiring harness between the sensor and BCM.
4
Step 4: Inspect both the sensor connector and BCM connector terminals for corrosion, bent pins, or moisture contamination. Clean or repair connectors as needed using electrical contact cleaner and dielectric grease.
5
Step 5: If wiring harness shows short to ground, trace the harness routing and repair or replace the affected section. If sensor shows internal short, replace the A/C Post Heater Sensor #2.
6
Step 6: Clear the code, verify sensor operation by monitoring live data for proper temperature readings, and perform a test drive with climate control cycling through various modes to confirm repair and ensure the code does not return.
Estimated Repair Cost
$120 - $450
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an abnormal voltage reading from the A/C Post Heater Sensor #2 circuit that is lower than expected, indicating a short circuit to ground. This sensor monitors the temperature of air after it passes through a secondary heater element...
The most common cause of B2429 (A/C Post Heater Sensor #2 Circuit Short to Ground) is: Damaged or chafed wiring harness causing the sensor signal wire to contact ground or metal body components
Typical repair costs for B2429 range from $120 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code does not affect vehicle safety or drivability and it is safe to continue driving. The primary impact is reduced climate control accuracy and comfort, as the HVAC system may not properly regulate cabin temperature.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2429 to identify the root cause.
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Quick Info
Category
Body
System
HVAC Climate Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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