2019-2020 Acura RLX: The Sport Hybrid's Critical Battery Cooling Radiator
This is not the main engine radiator; learn to spot the unique failure symptoms of the auxiliary radiator that protects your RLX's expensive hybrid battery.
- This is an AUXILIARY radiator for the HYBRID BATTERY, not the main engine. It only fits 2019-2020 RLX Sport Hybrid models.
- Failure symptoms are hybrid-specific: 'Check Hybrid System' warnings, reduced power, and poor MPG, not engine overheating.
- No aftermarket options exist, making a quality-inspected used OEM part the best value alternative to an expensive new one.
- A weak 12-volt battery can mimic hybrid system faults; always test the 12V battery before assuming a major component has failed.
Critical Compatibility Warning
For Sport Hybrid Models ONLY. This radiator, part number 1J010-R9S-014, is an auxiliary radiator for the hybrid battery cooling circuit. It will NOT fit non-hybrid Acura RLX models and cannot be used as a replacement for the main engine radiator.
Symptoms of a Failing Hybrid Battery Radiator
A problem with the hybrid battery's auxiliary radiator will not cause the engine to overheat. Instead, it triggers warnings related to the hybrid system itself. Look for these specific signs:
- Hybrid System Warning Lights: The most common symptom is a "Check Hybrid System" message on the dashboard. You may also see a red triangle warning light, indicating a serious fault that requires immediate attention.
- Reduced Power and Performance: To protect the battery from heat damage, the vehicle's computer may limit power, resulting in sluggish acceleration. This is sometimes referred to as "limp mode."
- Decreased Fuel Economy: When the hybrid battery is too hot, it operates inefficiently. The gasoline engine will run more often to compensate, causing a noticeable drop in your MPG.
- Erratic Battery Gauge: The battery charge level on the display may fluctuate wildly, jumping from full to empty in seconds. This indicates the battery cells are struggling due to heat.
- Visible Coolant Leaks: Like any radiator, this part can leak. You might notice a sweet smell of coolant or see puddles of blue or green fluid under the front of the car. The plastic end tanks are a common point of failure.
- Constantly Running Fans: If you hear a cooling fan running at high speed all the time, even in mild weather, the system is working overtime to cool an overheating battery.
Pro Tip: The Acura RLX Sport Hybrid is known for having a sensitive 12-volt electrical system. A weak or dying 12-volt battery (the standard car battery, not the main hybrid pack) can cause a cascade of random warning lights, including hybrid system errors. Before assuming a major hybrid component has failed, have your 12-volt battery tested first. 🎬 Watch: Understanding the critical role of your hybrid's 12v battery It's a common issue and a much cheaper fix.
Known Issues, Recalls, and TSBs
As of early 2026, there are no specific recalls or Technical Service Bulletins (TSBs) from Acura or the NHTSA for the auxiliary hybrid battery radiator (1J010-R9S-014) on the 2019-2020 Acura RLX. Recalls for this vehicle exist for other components like the fuel pump and timing belt, but none address the hybrid cooling system directly.
Buying a Used 2019-2020 RLX Hybrid Radiator
Since new aftermarket versions of this specialized radiator are not available, a quality used OEM part is an excellent value-based alternative to a new dealer part. Here’s what to look for when buying used:
- Verify the Part Number: Ensure the part is stamped with 1J010-R9S-014 or the earlier, interchangeable number 1J010-R9S-004. Do not accept any other part number.
- Inspect the End Tanks: Carefully check the black plastic tanks on the sides or top/bottom of the radiator. Look for hairline cracks, spiderwebbing, or any signs of previous repairs (like epoxy). This is the most common failure point.
- Check for Leaks: Look for chalky, colored residue (usually white, green, or pink) around the seams where the aluminum core meets the plastic tanks and around the hose connections. This indicates a past or current slow leak.
- Examine the Fins: The thin aluminum fins should be mostly straight. While a few bent fins from handling are okay, large areas of crushed fins will block airflow and reduce cooling efficiency.
- Look for Corrosion: Check the hose inlets and outlets for heavy corrosion or pitting, which could prevent a good seal with the coolant hoses.
Mileage is less of a concern than physical condition. A well-cared-for, high-mileage radiator is often a better bet than a low-mileage part from a vehicle that sustained a front-end collision.
Replacement Cost
Replacing the hybrid auxiliary radiator requires draining, refilling, and bleeding a dedicated cooling loop, which can be more complex than a standard engine radiator. Professional installation is recommended.
| Part or Service | Estimated Cost |
|---|---|
| New OEM (Acura Dealer) | $290 - $425 |
| New Aftermarket | Not Available |
| Used OEM | $100 - $225 |
| Shop Labor | $250 - $500 |
Frequently Asked Questions (FAQ)
Can I drive my RLX Hybrid if the battery cooling system has a problem?
It is not recommended. Driving with an overheating hybrid battery can cause irreversible damage to the battery cells, leading to a repair that costs thousands of dollars. If you see a hybrid system warning, you should have the vehicle inspected as soon as possible.
What kind of coolant does the hybrid auxiliary radiator use?
The hybrid system uses Honda/Acura Long Life Antifreeze/Coolant Type 2. This is a blue-colored coolant. Do not mix it with other colors or types of coolant, as this can cause damage to the system components.
Why can't I find a cheaper aftermarket version of this radiator?
The Acura RLX Sport Hybrid is a relatively low-production vehicle. Aftermarket manufacturers often do not produce specialized parts for less common models because the development costs cannot be justified by the low sales volume. This makes used OEM parts a particularly good value.
Is replacing this radiator a DIY job?
This is not recommended for most DIY mechanics. While the physical replacement is straightforward, the hybrid cooling system must be properly bled of air after refilling. Failure to do so can leave air pockets that prevent proper cooling and lead to battery damage. This procedure may require special tools or knowledge specific to hybrid vehicles.
🎬 Watch: How to properly refill and bleed a cooling systemHelpful Videos
Technical Specifications
OEM Part Numbers: 1J010-R9S-014 1J010R9S014
Replaces older part number: 1J010-R9S-004. Fits 2014-2020 Acura RLX Sport Hybrid models.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Acura RLX: