What Does B2428 Mean?
This code indicates the Body Control Module (BCM) has detected an electrical circuit malfunction in the A/C post-heater sensor #2. This sensor monitors temperature after the heater core or auxiliary heater to optimize climate control performance. The BCM has identified an open circuit, short to ground, short to power, or sensor internal failure that prevents proper temperature monitoring.
Common Causes
40%
Faulty A/C post heater sensor #2 with internal open or short circuit
30%
Damaged or corroded wiring harness or connector at sensor location
20%
Corroded or loose connector pins causing intermittent contact
10%
BCM internal fault or poor ground connection at BCM
Diagnostic Steps
1
Step 1: Perform visual inspection of A/C post heater sensor #2 location (typically near heater core outlet or auxiliary heater), checking for physical damage, corrosion, or disconnected wiring. Inspect connector for moisture intrusion or corroded pins.
2
Step 2: Using a digital multimeter, backprobe the sensor connector with ignition ON and measure voltage supply (typically 5V reference) and ground circuit continuity. Verify proper voltage at sensor connector matches manufacturer specifications.
3
Step 3: Disconnect sensor and measure resistance across sensor terminals at various temperatures using an ohmmeter. Compare readings to temperature-resistance chart for thermistor-type sensors (typically 2-10k ohms at room temperature).
4
Step 4: Check wiring harness continuity from sensor connector to BCM using a multimeter, testing for opens, shorts to ground, or shorts to power. Wiggle test harness while monitoring for intermittent faults.
5
Step 5: If wiring and sensor test good, verify BCM ground connections are clean and tight. Check BCM connector pins for corrosion or damage at the sensor circuit pins.
6
Step 6: After repairs, clear codes and perform a climate control system functional test including all temperature zones. Monitor live data to confirm sensor reading changes appropriately with temperature variations.
Estimated Repair Cost
$120 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an electrical circuit malfunction in the A/C post-heater sensor #2. This sensor monitors temperature after the heater core or auxiliary heater to optimize climate control performance. The BCM has identified an open circuit, short to grou...
The most common cause of B2428 (A/C Post Heater Sensor #2 Circuit Failure) is: Faulty A/C post heater sensor #2 with internal open or short circuit
Typical repair costs for B2428 range from $120 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this affects climate control comfort features only, not vehicle safety systems. Repair at convenience, though HVAC system performance and efficiency may be reduced until resolved.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2428 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Climate Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
