Parts for your 2006 Honda Elysion-Radiator cap

2006 Honda Elysion radiator cap: fitment, purpose and easy service advice

Based on technical sources, the 2006 Honda Elysion does use a radiator cap. The Honda Electronic Parts Catalogue for RR1–RR4 (Elysion) lists a pressure “Cap, Radiator (1.1)” P/N 19045-PAA-A01, and the 2004–2006 Honda Elysion Service Manual (Cooling System) specifies a pressurised cap and testing procedure. Honda service guidance also quotes a hold pressure in the 93–123 kPa range for a healthy 1.1 bar cap. On most Elysion variants the cap sits on the radiator’s filler neck at the top tank, some trims place the filler neck near the engine, but it’s still a proper pressure cap, not just a plain lid.

What does that cap actually do? It’s a small but critical bit of kit. The Elysion’s radiator cap seals the cooling system and holds about 1.1 bar of pressure (roughly 16 psi). That extra pressure lifts the coolant’s boiling point, helping the V6 or K24 engine keep its cool on hot days and big hills. Inside the cap is a vacuum valve too, which lets coolant return from the reservoir as the engine cools, so the system stays full without air pockets.

When a cap gets tired, it can cause annoying symptoms: slow coolant loss, the overflow bottle overfilling, soft or collapsing hoses as it cools, or a whiff of sweet coolant after a motorway run. Left unchecked, that can lead to overheating and bigger bills. That’s why it deserves a look during routine servicing.

Good practice for a 2006 Honda Elysion is to check the radiator cap at every service and any time coolant is changed. Only open it when the engine is stone cold. Inspect the rubber seals for nicks, hardening or swelling, check the spring action, and look for crusty deposits on the seat. A workshop can pressure-test the cap, for a 1.1 bar cap it should typically hold around 108 kPa within spec. If there’s any doubt, replace it — they’re inexpensive and can save a lot of grief.

When replacing, stick with the correct spec: a 1.1 bar cap such as Honda P/N 19045-PAA-A01 (or an equivalent quality cap to the same rating). Wipe the filler neck clean so the new seals bed properly, and make sure you’re opening the actual pressure cap (not just the translucent reservoir lid on other vehicles). Pair the job with fresh Honda Type 2 premix coolant at the recommended interval to keep everything under the bonnet tidy and reliable.

Popular questions about the 2006 Honda Elysion radiator cap

What pressure radiator cap does a 2006 Honda Elysion use?
It uses a 1.1 bar cap (about 108 kPa, 16 psi). The OEM Honda part number commonly referenced in the Honda EPC is 19045-PAA-A01. Using the correct pressure rating helps prevent boil-over and ensures proper coolant return as the engine cools.

Where is the radiator cap on an Elysion?
On most 2006 Elysion models it’s on the radiator’s top tank under the bonnet. Some variants have a separate filler neck near the engine, but it’s still a pressure cap. Don’t confuse it with the plastic coolant reservoir lid — that one isn’t the pressure cap.

How often should the cap be replaced?
Inspect it at every service. Many owners replace the cap during a coolant change or around 5 years/100,000 km, or immediately if it fails a pressure test or shows damage, weak spring tension, or perished seals.