MajorCommonCooling

Land Rover Defender: P300 2.0 Ingenium petrol thermostat housing coolant leak and low coolant warning

P300 2.0 Ingenium petrol thermostat housing coolant leak and low coolant warning is a common cooling fault on the Land Rover Defender on the 2020–2024 cars, and we rate it major. Putting it right costs $900 to $2,200 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 20 documented faults on the Land Rover Defender.

Vehicle: Land Rover Defender
Engine: 2.0L
Years: 2020–2024
Fuel: petrol
System: Cooling

This page covers the Land Rover Defender as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Land Rover Defender faults20 documented faults on this model

What you are looking at

An annotated photograph of an automotive engine thermostat identifying the wax capsule and both disc valves. — A double-valve engine thermostat, labelled: the wax capsule is what sticks.
Dougsim · CC BY-SA 3.0 · Wikimedia Commons

What goes wrong

On the P300 2.0 Ingenium four-cylinder turbo petrol, the plastic thermostat housing can leak coolant from its welded spigot cap or from the gasket where it meets the engine block. JLR issued Special Service Messages SSM76249 and SSM76248 covering 2020 to 2024 model year Defenders with this engine, and a separate message (SSM75918/SSM75919) for thermostat housings that stick open, logging code P0128 and giving poor cabin heat. Left alone, a slow leak becomes repeated low coolant warnings and eventually overheating, which can warp the aluminium head. There is no recall or extended warranty; the fix is a replacement housing, which is covered only while the car is inside its new-car warranty.

What you would notice

Low engine coolant warning on the dash, sometimes coming back after a top-up
Sweet coolant smell after a drive
Pink or white crusty residue around the thermostat housing on the engine
Slow warm-up or weak cabin heat, with the engine light on

How to check it

Where to look. Engine bay, thermostat housing on the 2.0 petrol engine block and the coolant expansion tank

With the engine cold, open the bonnet and check the coolant expansion tank level is between the MIN and MAX marks; a tank sitting at or below MIN on a car that has just been 'serviced' is a warning sign. Use a phone torch to look around the thermostat housing on the engine and along the hoses near it for pink crust, dried tide marks or damp patches. Look at the ground where the car is usually parked for drips. On the test drive, check the temperature reading settles and that the heater blows properly hot after 10 minutes. Ask whether the low coolant light has ever come on and whether the thermostat housing has been replaced under warranty, and ask for the invoice. If a workshop inspection is possible: have the cooling system pressure-tested cold and hot, and have stored codes read for P0128 or coolant level faults.

Parts involved: Thermostat.

What it costs to put right

$900 to $2,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the low coolant warning ever come on, and how often do you top it up?”
“Has the thermostat housing been replaced, and do you have the invoice?”
“Is the car still inside its new-car warranty?”

Now check the Land Rover Defender you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

JLR Special Service Message SSM76249 - Ingenium I4 2.0L Petrol Thermostat Housing Engine Coolant Leak (Defender L663 20-24MY)
JLR customer service bulletin compilation (NHTSA MC-11015273) citing SSM76249/SSM76248 for 20-24MY Defender
JLR SSM75918/SSM75919 - P0128 and poor cabin heating, replace thermostat housing (Ingenium I4 2.0L petrol, 18-23MY Defender)
LandRoverForums.com 2020 Defender 'Low coolant' thread (2020 P300 110 thermostat housing replaced)

Land Rover Defender buyer questions

Is p300 2.0 ingenium petrol thermostat housing coolant leak and low coolant warning serious on a Land Rover Defender?

We rate it major and common on the Land Rover Defender. On the P300 2.0 Ingenium four-cylinder turbo petrol, the plastic thermostat housing can leak coolant from its welded spigot cap or from the gasket where it meets the engine block. JLR issued Special Service Messages SSM76249 and SSM76248 covering 2020 to 2024 model year Defenders with this engine, and a separate message (SSM75918/SSM75919) for thermostat housings that stick open, logging code P0128 and giving poor cabin heat. Left alone, a slow leak becomes repeated low coolant warnings and eventually overheating, which can warp the aluminium head. There is no recall or extended warranty; the fix is a replacement housing, which is covered only while the car is inside its new-car warranty.

How much does it cost to fix on a Land Rover Defender?

$900 to $2,200 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Land Rover Defender years are affected?

Our research records this fault on the 2020–2024 Land Rover Defender. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.