Parts for your 2020 Ford Fiesta-Radiator cap

2020 Ford Fiesta “radiator-cap” — what’s actually fitted

On the 2020 Ford Fiesta there isn’t a traditional radiator cap on the radiator neck. Instead, the car uses a sealed cooling system with a pressurised coolant expansion tank (also called a degas bottle) that carries the pressure cap. Ford’s technical literature supports this setup: the Fiesta Owner’s Manual for this model year shows and labels a coolant reservoir with a warning not to open the cap when hot, and Ford workshop information (Engine Cooling, section 303‑03 for the Fiesta Mk8/B299 platform) describes a degas bottle as the system’s fill and pressure point, with no service cap on the radiator itself. That means a “radiator-cap” in the old-school sense isn’t used on the 2020 Fiesta.

Why the change? Modern Fiestas run a sealed, “degas” style system so the highest point is the plastic expansion tank under the bonnet. Keeping the pressure cap there does a few smart things: it improves bleeding and air separation, stabilises system pressure and boiling point, and lets the radiator sit low and compact for better packaging. The cap on the tank still does the classic pressure‑relief job, but it’s not on the radiator.

Servicing tip for owners and workshops: treat the coolant reservoir cap as a critical part. If its seals go hard or the spring weakens, the system can’t hold pressure properly, which can lead to coolant loss, overheating, or hoses collapsing as the car cools. A quick visual check and a pressure test during routine services is cheap insurance. Replace the cap if the O‑ring is nicked, if there’s dried coolant crust around the threads, if there’s a sweet coolant smell after drives, or if there are signs of overflow with normal driving. Always use a quality cap that matches the specified pressure rating printed on the original, and top up with coolant that meets the Ford specification listed in the owner’s handbook. Never crack the cap when the engine’s hot — wait until it’s fully cool to avoid a nasty burst of pressure and hot coolant.

• Common symptoms of a failing reservoir cap: coolant smell, visible residue around the cap, soft or collapsed hoses after cool-down, rising temps in traffic, or frequent low-level warnings.
• Good practice: inspect the cap at each service, replace proactively if in doubt, and renew the cap whenever the expansion tank itself is replaced.

FAQs

Does the 2020 Ford Fiesta have a radiator cap?
No. It uses a pressurised coolant expansion tank (degas bottle) with a cap, the radiator itself has no filler cap.

Which cap should be replaced on a 2020 Fiesta’s cooling system?
The coolant reservoir (expansion tank) cap. It’s the pressure cap for the system and should be inspected and replaced if seals are worn or if it won’t hold pressure.

How often should that cap be changed?
There’s no fixed interval. Have it checked at regular services, replace at the first sign of leaking, hard or cracked seals, or pressure test failure. Many owners choose preventative replacement every few years given the low cost.