Parts for your 2012 Honda Elysion-Radiator cap

2012 Honda Elysion radiator cap — what it does, and how to keep it in good nick

Technical documentation confirms the 2012 Honda Elysion is fitted with a pressure-type radiator cap. The Honda Elysion RR-series workshop manual (Cooling System — Radiator Cap Test) specifies a 1.1 bar cap, and the JDM Honda Electronic Parts Catalogue lists a genuine Honda/Denso 1.1 bar radiator cap for both K24A (2.4L) and J30A (3.0L V6) variants. Typical part references include Honda’s 1.1 bar cap used widely across contemporary models (e.g., 19045-PAA-A01 or superseding equivalents).

On the Elysion, the radiator cap does more than just seal the filler neck. It pressurises the cooling system so coolant can run hotter without boiling, helps purge air, and uses a vacuum valve to pull coolant back from the overflow bottle as things cool down. If the cap can’t hold pressure or the valve sticks, owners may see overflow bottle levels wandering about, sluggish heater performance, random temperature swings, or dried coolant crust around the neck under the bonnet.

As part of regular servicing, it’s worth giving the cap a quick once-over every 10,000–15,000 km. Look for perished rubber, corrosion, gunk on the sealing surfaces, or a weak spring. A workshop can pressure-test the cap with an adapter, if it can’t hold its rated 1.1 bar, it’s time for a replacement. When replacing, stick with the correct 1.1 bar cap for the Elysion — going lower can cause boil-over on a hot day in traffic, and going higher can stress hoses, the radiator, or the heater core.

Good habits help the cap last:

• Only open the cap when the engine is stone cold, cover it with a rag and crack it to the first stop to bleed off any residual pressure.
• Keep the filler neck clean so the rubber seals perfectly — a quick wipe at service time is enough.
• Use the right Honda-approved coolant mix and refresh it on schedule, old coolant can get acidic and chew out seals and springs.

If the Elysion is losing coolant with no obvious leaks, or the overflow bottle keeps filling and not returning, don’t ignore the radiator cap — it’s a cheap, simple fix that protects a very not-cheap engine.

Popular questions about the 2012 Honda Elysion radiator cap

What pressure cap does a 2012 Elysion use?
The Elysion uses a 1.1 bar (approx. 108 kPa) radiator cap as specified in Honda’s workshop procedures and parts catalogue for RR-series models. Using the correct pressure rating keeps the cooling system stable and protects components.

How often should the radiator cap be replaced?
There’s no hard expiry, but checking it at each service and replacing it every 4–5 years or if it fails a pressure test is a safe bet. Harsh conditions or neglected coolant can shorten its life.

What are signs the cap is failing?
Look for dried coolant around the neck, a coolant smell after parking, overflow bottle that keeps rising but doesn’t return after cool-down, random temp spikes, or soft/heater issues. A quick cap test will confirm it.