What Does B2380 Mean?
This code indicates the Body Control Module (BCM) has detected that the heater coolant temperature sensor circuit voltage is below normal operating range, consistent with a short to ground condition. The sensor monitors coolant temperature specifically for the HVAC heater system to optimize cabin heating performance. The BCM expects a resistance-based signal from this sensor, but instead detects a path to ground causing abnormally low voltage readings.
Common Causes
45%
Damaged or chafed wiring harness causing the signal wire to contact ground, commonly near engine mounting points or sharp metal edges
30%
Failed heater coolant temperature sensor with internal short to ground
15%
Corroded or moisture-contaminated connector terminals at sensor or BCM causing intermittent ground path
10%
BCM internal fault with sensor input circuit or damaged BCM connector pins
Diagnostic Steps
1
Step 1: Perform visual inspection of heater coolant temperature sensor, connector, and wiring harness from sensor to BCM. Look for chafed insulation, pinched wires, corrosion, moisture intrusion, or damaged connector pins.
2
Step 2: Disconnect heater coolant temperature sensor connector and measure resistance across sensor terminals using a digital multimeter. Compare reading to manufacturer specifications (typically 2,000-3,000 ohms at room temperature). A reading near 0 ohms confirms internal sensor short.
3
Step 3: With sensor disconnected, measure resistance from sensor signal wire terminal at harness connector to known good ground. Reading should be infinite (open circuit). Any continuity indicates wiring harness short to ground requiring trace and repair.
4
Step 4: Reconnect sensor if good, clear codes, and monitor sensor voltage at BCM connector using multimeter or scan tool live data. Signal should vary with temperature (typically 0.5-4.5V range). Verify voltage changes appropriately when engine warms up.
5
Step 5: If all wiring and sensor tests pass but code returns, perform BCM connector terminal inspection for bent pins, corrosion, or terminal push-out. Test BCM sensor input circuit per factory service manual procedures or consider BCM replacement if internal fault suspected.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected that the heater coolant temperature sensor circuit voltage is below normal operating range, consistent with a short to ground condition. The sensor monitors coolant temperature specifically for the HVAC heater system to optimize cabin he...
The most common cause of B2380 (Heater Coolant Temp sensor circuit Short to GND) is: Damaged or chafed wiring harness causing the signal wire to contact ground, commonly near engine mounting points or sharp metal edges
Typical repair costs for B2380 range from $75 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 cabin heating efficiency only and does not impact vehicle safety or critical systems. Repair at convenience, though cabin heating performance may be suboptimal in cold weather conditions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2380 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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