What Does P0A98 Mean?
The hybrid battery management system has detected that cooling fan 2 is running continuously and cannot be shut off. A stuck-on fan may indicate a shorted control circuit, a stuck relay, or a faulty controller. While excessive cooling is less immediately dangerous than overheating, it can drain the 12V auxiliary battery, create excessive cabin noise, and may mask an underlying control circuit failure.
Common Causes
35%
Shorted fan relay or fan controller module holding the circuit closed
25%
Short to power in the fan control circuit wiring harness
20%
Hybrid battery ECU internal fault commanding fan on continuously
15%
Faulty battery temperature sensor reporting erroneously high temperatures, causing constant fan operation
5%
Fan motor internal short causing it to run whenever power is available to the circuit
Diagnostic Steps
1
With the vehicle in READY mode, use the scan tool to monitor the commanded state of cooling fan 2. Verify whether the ECU is actively commanding it on or if it is running independently of ECU control.
2
If the ECU is not commanding the fan on, disconnect the fan relay and check if the fan stops. A fan that continues running with the relay removed indicates a short to power in the wiring downstream of the relay.
3
Check hybrid battery temperature sensor readings via scan tool. Compare sensor A readings to ambient/expected values — an erroneously high reading will cause the ECU to legitimately command maximum cooling.
4
Inspect the fan control relay for welded contacts by measuring resistance across the relay contacts with it removed — contacts should read open when de-energized. Replace if welded closed.
5
Trace the fan control circuit wiring for chafing or insulation damage that could cause a short to battery voltage. Pay attention to routing near sharp edges or hot components.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The hybrid battery management system has detected that cooling fan 2 is running continuously and cannot be shut off. A stuck-on fan may indicate a shorted control circuit, a stuck relay, or a faulty controller. While excessive cooling is less immediately dangerous than overheating, it can drain the ...
The most common cause of P0A98 (Hybrid Battery Pack Cooling Fan 2 Stuck On) is: Shorted fan relay or fan controller module holding the circuit closed
Typical repair costs for P0A98 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A continuously running fan primarily causes excessive 12V battery drain (which could leave you stranded) and elevated cabin noise. In rare cases, overcooling the battery in cold weather could reduce performance. The vehicle is generally safe to drive short distances, but diagnose promptly to avoid auxiliary battery depletion.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0A98 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid Battery Thermal Management
Difficulty
Type
Generic (SAE)
Recommended Tools
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