ERR4686 - Filler Plug – Plastic

- €3,70

€3,70

€3,70 - €3,70

€3,70

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Aftermarket: Quality alternative. This is a quality alternative, designed to fit and function like the original part, often at a more competitive price.

Filler Plug sealing the fill and bleed point of the engine cooling system, fitted to the thermostat housing and the radiator.

This plastic plug closes the top-up and bleed port and maintains cooling system integrity under operating pressure on Tdi and V8 applications. It is sealed by O-ring ESR4685, which should be renewed each time the plug is removed.

Vehicle Model Land Rover Defender up to 2016
Land Rover Discovery 1 1989-1998 (L318)
Land Rover Discovery 2 1998-2004 (L318)
Range Rover Classic up to 1994
Range Rover Classic 1994-2001 (P38)
Land Rover Series 2 and 3

Fitment Notes Plug - drain / filler level, engine cooling system (radiator and thermostat housing)
DEFENDER 1987-2006 — Radiator (2.5 TDi Non-EGR / 4-cyl TDi); Thermostat Housing (2.5L I4 300TDi)
DISCOVERY 1 1989-1998 — Thermostat Housing, 2.5 TDi EGR (Gem) / 2.5L 300TDi (to VIN MA081992)
RANGE ROVER P38 1994-2001 — Radiator and cooling system, 4.0L & 4.6L V8 Petrol
RANGE ROVER CLASSIC 1992-1994 (from VIN JA610294) — Thermostat Housing, 2.5L TDi

Alternative Codes

ERR4686607024ARA2404BR 3485BR 3485BNTC4609

In stock 4 units

3 · Gouda 1 · Drachten

Express delivery available

When will my order arrive?

Order before 15:00 (Mon–Fri): same-day dispatch for in-stock items.
UPS Express (order before 14:00): dispatched today, delivered tomorrow where available.
Netherlands / Belgium / Germany: 2–4 working days.
Other EU countries + UK: 4–8 working days.
Outside EU/UK: delivery times vary — contact us for an estimate.

Items may ship from multiple warehouses at no extra cost.

Job kits containing this part

This part is included in 0 job kit(s) below. Pick the kit that matches your vehicle and job, then add what you need.

Frequently asked questions

What is the ERR4686 filler plug and what does it do?

The ERR4686 filler plug is a plastic plug that seals the fill and bleed point of the cooling system, fitted to the thermostat housing or radiator. It closes the top-up port and holds cooling system pressure on Tdi and V8 applications across the Defender, Discovery and Range Rover range.

Does the filler plug need a new seal when refitted?

Yes, the filler plug is sealed by a separate O-ring that should be renewed every time the plug is removed. Reusing an old O-ring typically causes coolant seepage or pressure loss from the bleed point on a 300TDi or V8 cooling system. The plug itself is reusable if undamaged.

Which cooling system does the ERR4686 fit on?

The ERR4686 fits the radiator on Tdi Defenders and the thermostat housing on 300TDi engines, plus the cooling system on Range Rover P38 4.0 and 4.6 V8 petrol. Note the Discovery 1 application runs to VIN MA081992, so check your VIN before ordering.