What Does This Error Mean?

Land Rover coolant temperature warning means the engine is overheating — stop and switch off the engine immediately. Range Rover and Discovery engines are expensive to repair — a single severe overheating event can cause head gasket or cylinder head failure.

Affected Models

Range Rover (L405/L460)
Range Rover Sport
Range Rover Evoque
Land Rover Discovery
Land Rover Discovery Sport
Land Rover Defender (L663)

Common Causes

Low coolant level from a hose or radiator leak
Thermostat stuck closed — particularly common on older 4.4 TDV8 and 3.0 TDV6 diesel engines
Electric auxiliary water pump failure — used on turbocharged petrol models
Radiator fan failure
EGR cooler failure on TDV6 and TDV8 diesel engines — can cause coolant loss into the combustion chamber

How to Fix It

Stop and switch off the engine.

Pull over safely and switch off the engine as soon as the temperature warning appears. Turning the cabin heater to maximum briefly draws heat away from the engine. Land Rover diesel engines — TDV6 and TDV8 — are particularly vulnerable to EGR cooler failure during overheating events.
Wait before opening the cooling system.

Pressurized coolant is extremely hot when the engine overheats — wait at least 30 minutes before touching the expansion tank cap. The expansion tank is typically a white plastic tank in the engine bay with a pressure cap. Cover the cap with a thick cloth and turn slowly to release pressure.
Check the coolant level.

After cooling, check the expansion tank against the MIN and MAX marks. Range Rover and Land Rover models use OAT coolant (usually blue or pink — check the cap). If the level is consistently dropping, find and repair the source — EGR cooler failure on TDV6 diesel engines causes internal coolant loss into the exhaust system.
Check the electric auxiliary water pump on petrol models.

Range Rover AJ200 and AJ126 petrol engines use an electric auxiliary water pump. A failed auxiliary pump causes overheating at idle and low speed — but not at motorway speeds where the main pump provides adequate flow. A fault code for the auxiliary pump appears in the engine management system.
Check for EGR cooler failure on TDV6 and TDV8 diesels.

Land Rover TDV6 and TDV8 diesel engines in the Discovery 3/4 and Range Rover Sport L320 are documented for EGR cooler failure. Symptoms include white smoke from the exhaust, sweet-smelling exhaust, and unexplained coolant loss. EGR cooler failure causes coolant to enter the exhaust and eventually the engine — this is a serious fault requiring immediate professional attention.

When to Call a Professional

After any overheating event on a Range Rover or Land Rover Discovery, have the head gasket integrity checked with a combustion gas test before returning to use — the cost of checking is far less than the cost of a failed head gasket.