Hybrid Battery Pack Cooling Fan 2 Stuck On
The P0A98 code indicates that the hybrid battery pack cooling fan 2 is running continuously even when the engine is off or the battery is not hot. This fan is part of the thermal management system for the high-voltage hybrid battery. When stuck on, it can drain the 12V auxiliary battery and reduce fuel economy. The issue is often caused by a faulty fan relay, a shorted fan motor, or a malfunctioning battery temperature sensor that keeps the fan circuit energized.
1. Symptoms You Will Notice
- Cooling fan 2 runs continuously even with key off
- Dead 12V battery after sitting overnight
- Reduced fuel economy due to parasitic drain
- Possible check engine light with P0A98
2. Most Common Causes
- Faulty cooling fan relay stuck closed
- Shorted fan motor causing continuous operation
- Defective battery temperature sensor sending false hot signal
- Wiring short to power in the fan control circuit
3. Step-by-Step Diagnosis
Step 1: Verify fan 2 operation with key off; listen for fan noise under rear seat or trunk.
Step 2: Check for parasitic draw on 12V battery using a multimeter; pull fan relay to see if draw drops.
Step 3: Inspect fan relay and replace if stuck closed.
Step 4: Test fan motor resistance; replace if shorted.
Step 5: Scan hybrid battery temperature sensor data; replace sensor if reading abnormally high.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Driving short distances is possible, but the continuous fan drain can kill the 12V battery, leaving you stranded. It's best to fix it promptly.
How much does it cost to fix?▼
Typically $50-$150 for a relay or sensor replacement; a fan motor replacement may cost $200-$400 including labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.