2014-2020 Acura RLX Sport Hybrid Battery Radiator: Failure Warnings & Replacement Guide

Critical Compatibility Warning

Symptoms of a Failing Hybrid Battery Radiator

A problem with the hybrid battery's auxiliary radiator will not cause the engine's temperature gauge to rise. Instead, it triggers warnings related to the Intelligent Power Unit (IPU), which is the heart of the hybrid system. Look for these specific signs:

• Hybrid System Warning Lights: This is the most common symptom. You will see a "Check Hybrid System" message on the multi-information display (MID). A general malfunction indicator lamp may also illuminate.
• Reduced Power and Performance: To protect the battery from overheating, the vehicle's computer will limit the amount of electrical assist, resulting in noticeably sluggish acceleration. The car may feel much slower than usual.
• Visible Coolant Leaks: Like any radiator, this part can leak. You might notice puddles of blue-colored fluid under the front driver's side of the car. A sweet, syrupy smell is also a key indicator of a coolant leak. The plastic end tanks are a common failure point where leaks can develop from hairline cracks.
• Constantly Running Cooling Fans: If you hear the front cooling fans running at high speed constantly, even in mild weather or shortly after starting the car, it's a sign the system is struggling to bring the hybrid component temperatures down.
• Erratic Battery Gauge or Performance: The high-voltage battery charge level on the display may fluctuate more than usual, or the vehicle may be unwilling to enter EV (electric-only) mode as it tries to protect the battery.

Known Issues, Recalls, and TSBs

As of mid-2024, there are no specific recalls or Technical Service Bulletins (TSBs) issued by Acura or the National Highway Traffic Safety Administration (NHTSA) for the failure of this auxiliary hybrid radiator (part numbers 1J010-R9S-004, 1J010-R9S-014) on the 2014-2020 Acura RLX Sport Hybrid. While numerous recalls exist for the RLX for other components like fuel pumps and headlights, the hybrid cooling system has not been the subject of a specific campaign.

Buying a Used Hybrid Radiator: What to Look For

Since new aftermarket versions of this specialized radiator are generally not available, a quality-inspected used OEM part is the best value-based alternative to a new dealer part. Here's what to inspect:

• 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 Plastic End Tanks: This is the most common failure point. Carefully check the black plastic tanks on the radiator. Look for hairline cracks, chalky white residue (from dried coolant), or any signs of previous repairs like epoxy or sealant.
• Check the Fins: The aluminum fins should be mostly straight. A few bent fins from handling are okay, but large areas of crushed fins will reduce cooling efficiency. Ensure there's no heavy corrosion or 'flaking' of the aluminum.
• Examine Hose Connections: Look at the inlet and outlet ports. They should be round and free of cracks or damage that could prevent a hose from sealing properly.
• Mileage vs. Condition: For a radiator, physical condition is more important than mileage. A low-mileage part from a front-end collision could be damaged, while a higher-mileage part with no signs of leaks or corrosion can be a perfectly good component.

Cost of Replacement

The cost to replace the RLX Sport Hybrid auxiliary radiator can vary based on your location and choice of parts. The high estimates often found online are typically for the main engine radiator, which is a larger and more labor-intensive job.

Replacement Procedure Overview

Replacing this radiator is feasible for an experienced DIY mechanic, but caution is required due to the hybrid system. If you are not comfortable working with hybrid vehicle cooling systems, this job is best left to a professional.

1. Disconnect the 12V Battery: Always disconnect the negative terminal of the 12-volt battery before starting work.
2. Access the Radiator: This may require removing the front bumper cover and/or splash shields to get to the radiator, which is located on the driver's side.
3. Drain the Coolant: Locate the drain plug (petcock) on the auxiliary radiator or the lowest hose connection. Drain the coolant into a clean container. This loop holds less coolant than the main engine system.
4. Disconnect Hoses & Mounts: Remove the clamps and disconnect the inlet and outlet hoses. Unbolt the radiator's mounting brackets.
5. Remove and Install: Carefully remove the old radiator and install the new one, ensuring any rubber mounting grommets are transferred if necessary.
6. Reconnect and Refill: Re-attach the mounting brackets and hoses. Refill the system slowly with Honda/Acura Long Life Antifreeze/Coolant Type 2 (blue). Do NOT use universal green or orange coolant.
7. Bleed the System: This is the most critical step. The hybrid cooling system must be properly bled of all air to function correctly. This may involve running the vehicle's internal coolant pump via a diagnostic tool or following a specific manual procedure. An air-locked system will not cool properly and will trigger warnings. A spill-free funnel is highly recommended.
8. Check for Leaks: Once bled, run the vehicle and check thoroughly for any leaks before re-installing the bumper or other body parts.

Frequently Asked Questions (FAQ)