P0A98 — Hybrid Battery Pack Cooling Fan 2 Stuck On

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution and watch the temperature gauge. A thermostat stuck open mainly costs fuel; any sign of overheating means stop immediately — driving an overheating engine destroys head gaskets and worse.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0A98 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the engine cooling and temperature control for damage, corrosion, chafing or poor contact.
Subsystem check Command the hybrid battery pack cooling fan 2 on and off with a scanner and watch the feedback signal; then remove and inspect the mechanism for sticking before replacing it.
Subsystem check Watch coolant temperature in live data during warmup — it should climb smoothly to operating temperature.
Subsystem check Check coolant level and feel upper/lower radiator hoses to verify thermostat operation.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0A98 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0A98 (parts and labor, USD, independent shop rates): Replace the thermostat: $150–$400; Replace the coolant temperature sensor: $100–$300; Cooling system repair (pump, fan, radiator): $300–$1,200. Overall, fixing P0A98 usually costs between $100 and $1,200. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Will P0A98 clear itself?

Sometimes P0A98 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What does OBD2 code P0A98 mean?

Hybrid Battery Pack Cooling Fan 2 Stuck On (P0A98): a powertrain (engine/transmission) fault affecting the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Most often caused by thermostat stuck open or closed, faulty coolant temperature sensor, failed cooling fan or fan relay.

What is the most common cause of P0A98?

The most common causes are: thermostat stuck open or closed, faulty coolant temperature sensor, failed cooling fan or fan relay.

How much does it cost to fix P0A98?

Replace the thermostat — $150–$400; Replace the coolant temperature sensor — $100–$300; Cooling system repair (pump, fan, radiator) — $300–$1,200. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Is it safe to drive with P0A98?

Drive with caution and watch the temperature gauge. A thermostat stuck open mainly costs fuel; any sign of overheating means stop immediately — driving an overheating engine destroys head gaskets and worse.

When your vehicle's computer detects that the second hybrid battery pack cooling fan refuses to cycle off—or activates when it shouldn't—it stores trouble code P0A98. The powertrain control module constantly monitors feedback from the cooling fan circuit. When the actual state of the fan contradicts the commanded state for longer than acceptable, P0A98 gets set. This code lives in the powertrain category because it involves the thermal management system that protects your engine and hybrid components.

The hybrid battery pack cooling fan plays a critical role in maintaining safe operating temperatures for your vehicle's high-voltage battery and related electronics. When this fan stays locked in the "on" position, it continuously draws power and disrupts the normal cooling cycle. The engine control unit tracks fan operation through a feedback signal; if that signal shows the fan running when the module told it to shut down, or remaining stationary when it should be spinning, the fault is flagged. P0A98 typically requires multiple failed attempts to change fan state before the check engine light activates. The module also captures a freeze frame—sensor readings at the exact moment of failure—which becomes your roadmap for diagnosis.

Understanding why P0A98 appears means recognizing that modern thermal management relies on precise coordination between sensors, actuators, and control modules. A single point of failure anywhere in this chain can trick the ECU into logging this code. The good news is that the root cause is usually mechanical—something you can see and fix—rather than a mysterious electrical ghost.

Common Symptoms of P0A98

Cooling fans that never stop running, even after the engine reaches normal operating temperature
Noticeable spike in fuel consumption because the fan motor draws continuous power
Weak or insufficient cabin heating because coolant isn't reaching proper operating temperature
Temperature gauge hovering below normal or failing to climb as expected
Occasional overheating warnings, particularly under heavy load or stop-and-go traffic
Illuminated check engine light on the dashboard

What Triggers P0A98?

Welded relay contacts holding the fan circuit in a permanent "on" state
A failing actuator motor inside the fan assembly or a broken return spring preventing shutoff
Mechanical binding caused by carbon buildup, accumulated dirt, or corrosion on fan blades or bearings
A faulty coolant temperature sensor sending incorrect readings to the control module
A thermostat stuck in the open position, preventing proper warm-up
Wiring damage such as chafed insulation, corroded connectors, or loose terminals in the fan circuit
Low coolant level or trapped air pockets disrupting the thermal feedback loop

Diagnosing P0A98

Connect an OBD2 scanner and confirm P0A98 is stored in the ECU. Save the freeze frame data immediately—this snapshot of engine speed, load, coolant temperature, and vehicle speed pinpoints the conditions under which the fault occurred.
Pull all stored codes. P0A98 sometimes appears alongside other temperature-related codes that point to the real culprit. Check for manufacturer TSBs related to your specific make, model, and model year—many cooling fan issues have documented factory fixes or calibration updates.
Inspect the wiring harness and electrical connectors feeding the hybrid battery pack cooling fan. Look for damaged insulation, green corrosion on terminals, broken wires, or connectors that aren't fully seated.
Use your scanner to command the fan on, then off, while monitoring the feedback signal. If the fan doesn't respond to commands, remove it and physically check the blades for free movement and the motor for binding.
Monitor live coolant temperature data during a warm-up cycle. Normal operation shows a steady climb to approximately 195–210°F. A thermostat stuck open causes sluggish warm-up and consistently low readings.
Verify coolant level and squeeze the upper and lower radiator hoses to confirm the thermostat opens at the correct temperature.

Repair Options and Costs for P0A98

Address the cheapest probable causes before replacing major components:

Thermostat replacement: $150–$400
Coolant temperature sensor replacement: $100–$300
Cooling system repair (water pump, fan motor, radiator): $300–$1,200

How Much Does Fixing P0A98 Cost?

Parts and labor for P0A98 repairs at independent shops typically break down as follows: thermostat replacement runs $150–$400 depending on vehicle complexity and parts pricing. Coolant temperature sensor work costs $100–$300 in most cases. Full cooling system repairs involving the water pump, fan motor assembly, or radiator range from $300 to $1,200 based on what requires attention. In total, expect to spend anywhere from $100 on the low end to $1,200 if extensive work becomes necessary. Getting an accurate diagnosis before purchasing parts is the smartest move—the most expensive scenario is rarely where you should start.

Can You Drive with P0A98?

Use caution. A stuck-open thermostat mainly costs you fuel and comfort. However, if the temperature gauge climbs into the danger zone or you see overheating warnings, pull over immediately and shut down the engine. Continuing to drive an overheating vehicle risks catastrophic head gasket failure, warped cylinder heads, and permanent engine damage. Keep a close eye on that temperature gauge and treat any sign of overheating as an emergency.