Parts for your 2010 Honda Odyssey-Radiator cap

2010 Honda Odyssey radiator cap — what it does, where it is, and when to replace it

Yes, a radiator cap is fitted to the 2010 Honda Odyssey. This comes straight from technical sources: Honda’s service manual for the 2005–2010 Odyssey details removing the radiator cap during cooling system service and bleeding, and Honda’s EPC lists an OEM cap (1.1 bar/16 psi, commonly referenced as 19045-PAA-A01) for this model. Major aftermarket catalogues (e.g., Stant and Gates application guides) also specify a direct-fit cap for the 2010 Odyssey.

On this Odyssey, the radiator cap is a small but critical pressure valve that keeps the cooling system pressurised so coolant can run hotter without boiling. That extra pressure lifts the boiling point, helping the 3.5‑litre V6 manage heat in Aussie and Kiwi conditions, whether it’s school runs, summer motorway stints, or towing. The cap also works in both directions: under heat it lets expanding coolant move into the overflow bottle, and as the engine cools it draws that coolant back, keeping things topped up.

Owners can expect a few easy wins from a healthy cap: steadier operating temps, less coolant loss, and reduced stress on hoses and the radiator. On the 2010 Odyssey, it’s located on the radiator neck under the bonnet. Always open it only when the engine is cold.

• Check the cap at each service: inspect the rubber seal for cracks, the spring for stiffness, and the seat for corrosion or crusty deposits.
• Watch for tell‑tales like random overheating, sloshing into the overflow bottle, collapsed upper hose after cool‑down, or a sweet coolant smell.
• Use the correct spec: a 1.1 bar (16 psi) cap. Lower pressure can cause boil‑over, higher can stress hoses and the radiator.
• If in doubt, replace every 5 years or ~100,000 kilometres, or any time the cap fails a pressure test.

When replacing, stick with an OEM‑quality cap. With the engine cold, twist the old cap to the first stop to vent, remove it, top up with Honda Type 2 blue coolant (50/50 premix), and refit the new cap firmly. After a coolant service, run the engine with the heater on hot to purge air, recheck levels in both the radiator and overflow bottle, and set the bottle to the MAX line. It’s a quick, low‑cost bit of maintenance that helps the Odyssey stay cool, reliable, and ready for the long haul.

Where is the radiator cap on a 2010 Honda Odyssey?
It sits on the radiator filler neck under the bonnet, typically near the upper radiator support. Lift the bonnet, look towards the top of the radiator assembly, and you’ll spot the twist‑on cap. Some models have a small cover or shroud, remove that for better access.

Only open the cap when the engine is cold. If you can’t see it clearly, follow the upper radiator hose to the radiator — the cap is right nearby.

What pressure rating should the cap be?
The correct rating is 1.1 bar (about 16 psi). That matches Honda’s specification for the 2010 Odyssey and maintains the right system pressure to raise the boiling point without over‑stressing components.

Using a cap with the wrong rating can cause overheating, coolant loss, or premature hose and radiator wear.

Can a bad radiator cap cause overheating or coolant loss?
Absolutely. A weak spring or damaged seal can let pressure escape early, pushing coolant into the overflow bottle and out onto the ground, or drawing air back in as the engine cools. Either way, the system can run low and overheat.

If there’s intermittent overheating, visible leaks near the bottle, or a collapsed upper hose after cool‑down, the cap is a prime suspect — easy to test and cheap to replace.