Honda 19045-PWA-004 Radiator Cap

✔ Honda 19045-PWA-004 Radiator Cap — Genuine OEM Part
✔ Fitment: L-series and R-series engines in Civic, Fit/Jazz, HR-V, and other select models
✔ Direct replacement for factory radiator cap — no modifications required
✔ Manufactured to Honda's original specifications and tolerances
✔ Pressure rating: 1.1 bar (110 kPa) — maintains proper cooling system pressure

Honda 19045-PWA-004 Genuine Radiator Cap — 1.1 bar (110 kPa)

Coolant leaks from the radiator neck, engine overheating at idle or under load, a low coolant level warning, or steam coming from under the hood — these are common signs that your radiator cap is failing. A worn or stuck cap can cause coolant loss, pressure loss, and overheating, which can lead to severe engine damage. Replacing it with this genuine Honda cap restores proper cooling system pressure and protects your engine.

This is a factory-original Honda radiator cap (OE part number 19045-PWA-004) with a 1.1 bar (110 kPa) pressure rating. It is engineered with a calibrated pressure relief valve and a vacuum valve to maintain the correct operating pressure in the cooling system, preventing coolant boiling and reducing the risk of hose and radiator damage. This is the same part sold at Honda dealerships.

OEM Part Numbers
• 19045-PWA-004
• 19045-PWA-003 (superseded)

Compatible original part numbers (OEM)

Vehicle Fitment Table (OEM Compatibility)

⚠️ Important Fitment Notes:

• Always verify by VIN – Fitment is determined by the specific cooling system and pressure rating. Some models listed above also came with different radiator caps (e.g., 1.3 bar) — check your original cap before ordering.

• Pressure rating – This cap is rated at 1.1 bar (110 kPa). If your original cap is 1.1 bar, this is a direct replacement. Do not use a 1.3 bar cap unless the system is designed for it.

• Supersession – Part 19045-PWA-004 directly replaces and supersedes the older number 19045-PWA-003. It is fully backward‑compatible.

• Double‑check your original part – Before ordering, confirm the part number stamped on your old cap or run your VIN through a Honda OEM parts catalog for absolute certainty.

When to Replace (Common Symptoms)
• Coolant leaks from the radiator neck or cap area
• Engine overheating at idle or under load
• Low coolant level warning or coolant loss
• Steam or coolant spray from under the hood
• The cap does not hold pressure (can be tested with a pressure tester)
• Damaged or cracked rubber gasket on the cap
• Visible corrosion on the cap or radiator neck

Product Highlights
• ✔ Genuine Honda OEM part — not an aftermarket or Chinese replica
• ✔ Calibrated pressure relief valve opens at 1.1 bar (110 kPa) for optimal cooling system protection
• ✔ Integrated vacuum valve allows coolant to flow back from the reservoir when the engine cools
• ✔ High-temperature resistant rubber gasket for a leak-free seal
• ✔ Made from corrosion-resistant materials for long service life
• ✔ Backed by Honda’s manufacturer warranty (valid through any authorized dealer)

Condition
New (100% genuine Honda packaging)

Product Type
Radiator Cap (pressure cap with integrated relief and vacuum valves)

Function
Maintains the correct pressure in the engine cooling system, raising the boiling point of the coolant and preventing cavitation. The pressure relief valve releases excess pressure to protect hoses and the radiator, while the vacuum valve allows coolant to return from the overflow tank as the engine cools.

Applications
This radiator cap fits Honda L-series (L15A, L15B, LDA, LEA) and R-series (R18A, R18Z1) engines found in Civic (8th–9th gen), Fit/Jazz (2nd–3rd gen), HR-V (1st gen), Insight (2nd gen), and CR-Z (1st gen) from approximately 2006 through 2020. It is not compatible with K-series, J-series (V6), or older D-series engines.

Important: Always use the VIN (Vehicle Identification Number) to confirm compatibility with your specific vehicle. If in doubt, send us your VIN before ordering and we’ll verify for you.

Package Contents
• 1 × Honda 19045-PWA-004 radiator cap (genuine)

Technical Specifications

Warranty
Honda's original manufacturer warranty applies. For claims, please contact your nearest Honda authorized dealer with your proof of purchase. Warranty terms may vary by region — contact us before purchase if you need a warranty confirmation.

FAQ

Is this a genuine Honda part or a copy?
This is 100% genuine Honda OEM — in original factory packaging with Honda part number printed on the box. It is not an aftermarket brand or a replica.

Does this fit my 2010 Honda Fit with the L15A engine?
Yes — your Fit (2nd gen) with the 1.5L L15A engine requires this 1.1 bar cap. We recommend verifying with your VIN for absolute certainty.

What’s the difference between 19045-PWA-003 and 19045-PWA-004?
004 is the superseded part number — it replaces 003. 004 includes an updated rubber gasket material for improved long-term durability. It is fully backward-compatible.

Can I use a 1.3 bar (130 kPa) cap instead?
No — using a higher-pressure cap can damage your radiator, hoses, or water pump. Always use the pressure rating specified for your vehicle (1.1 bar for this cap).

How do I know if my radiator cap is bad?
Check for visible cracks in the rubber gasket, coolant residue around the cap, or overheating. You can also take it to a shop for a pressure test — it should hold 1.1 bar.

Does this fit my 2012 Honda Civic with the R18 engine?
Yes — the 8th–9th gen Civic with R18 uses this 1.1 bar cap. Please check your original cap number to be sure.

Will this cap fit the Honda CR-V?
No — CR-V with K-series engines uses a different radiator cap (usually with a higher pressure rating). Please check your original part number before ordering.