Motor Electronics Coolant Pump Control Circuit Open
The P0B38 code indicates an open circuit in the control circuit of the motor electronics coolant pump, which is responsible for circulating coolant through the inverter and electric motor in hybrid/electric vehicles. This can lead to overheating of the power electronics, potentially causing reduced performance or damage.
01. Most Common Causes
- Faulty motor electronics coolant pump
- Open or shorted wiring in the pump control circuit
- Damaged connector or poor electrical connection
- Failed pump relay or fuse
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Overheating of electric drive components
- Reduced vehicle performance or limp mode
- Coolant leaks near the pump
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Visually inspect the coolant pump and its wiring for damage or corrosion.
Step 3: Test the pump's electrical connector for voltage and ground signals using a multimeter.
Step 4: Check the pump's resistance; compare to manufacturer specifications.
Step 5: If signals are missing, inspect the fuse, relay, and wiring back to the control module.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. Driving with an open circuit can cause the coolant pump to fail, leading to overheating of the motor electronics and potential damage to expensive components. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts and labor. The pump itself costs $50-$150, and labor adds $100-$250 depending on the vehicle.