Parts for your 2020 Audi Q5-Radiator cap

2020 Audi Q5 radiator cap — is there one?

The 2020 Audi Q5 doesn’t use a traditional radiator cap mounted on the radiator itself. Instead, it runs a sealed, pressurised cooling system that’s filled and vented through a screw cap on the coolant expansion tank (the translucent reservoir in the engine bay). So if someone’s hunting for a “radiator cap” on a Q5, they won’t find one — the cap to care about is on the expansion tank.

This layout is how Audi designed the FY-series Q5 cooling system. It places the expansion (degas) tank at a high point so air can separate out of the coolant, and it centralises pressure control at the tank cap. You top up and check the level only at that reservoir, the radiator remains a closed component with no filler neck.

Why Audi doesn’t use a radiator cap on the Q5:

• System design: A remote expansion tank handles filling, deaeration and pressure regulation more reliably than a neck on the radiator.
• Packaging and safety: Modern front-end modules are tightly packed and shrouded. Keeping a hot, pressurised cap away from the radiator core reduces scald risk and damage from accidental opening.
• Multiple coolant circuits: Turbocharger and charge-cooling loops benefit from a single, high-point tank to purge air and maintain stable pressure.
• Serviceability: Technicians fill and bleed via the expansion tank (and, in workshops, vacuum-fill tools) for consistent results and fewer airlocks.

Technical sources backing this setup:

• Audi 2020 Q5 Owner’s Manual: directs coolant checks and top-ups at the expansion tank only, no radiator cap is shown or referenced.
• Audi workshop information (ElsaPro): cooling system diagrams label the “coolant expansion tank cap” as the pressure-control point, the radiator has no filler cap.
• Audi/VW Group parts catalogue (ETKA), cooling system group: lists a cap for the coolant expansion tank and no separate radiator filler cap for FY-series Q5.

If the cap you’re chasing is for servicing, look for the black or blue screw cap on the coolant reservoir under the bonnet. Only open it when the engine is completely cold, and use the correct OAT coolant (G12/G12evo family) mixed to the specified ratio. If there’s any sign of coolant smell, white-pink residue around the cap, or the system isn’t holding pressure, the expansion tank cap is a replaceable service item and should be inspected or swapped.

FAQs

Where is the coolant cap on a 2020 Audi Q5?
It’s on the translucent coolant expansion tank in the engine bay. That’s the only place Audi intends you to open for level checks or top-ups. There’s no cap on the radiator itself. Always wait until the engine is cold before loosening it.

What pressure is the cap, and does it need replacing?
The expansion tank cap is a pressure-rated safety valve (commonly around 1.4–1.6 bar on modern Audi systems). If the seal goes hard or cracked, or you notice coolant odour, dried pink residue, or repeated low-level warnings, the cap can be replaced as a maintenance item.

Can a traditional radiator cap be fitted to the Q5’s radiator?
No. The radiator has no filler neck by design. Adding one would defeat the sealed, high-point expansion system and can cause aeration and pressure issues. Stick with the factory tank cap only.