Parts for your 2025 Suzuki Splash-Thermostat

2025 Suzuki Splash Thermostat — what it does and when to replace it

Based on technical sources such as Suzuki dealer parts catalogues (EPC), the Suzuki Splash workshop/service manuals for K10B/K12B petrol engines, and the Fiat/GM 1.3 DDiS (Multijet) cooling system documentation used in the Splash diesel, the model family is built with a conventional wax‑pellet engine coolant thermostat. There isn’t a Splash variant documented without a thermostat, and later production updates retained a thermostat as a core cooling‑system component. So for any Splash referred to as a 2025 model or compliance import, a thermostat is fitted and relevant to servicing.

This thermostat sits in the cooling circuit and regulates flow to the radiator, helping the engine warm up quickly and then holding it near its ideal operating temperature. That means better fuel economy on the morning commute, steadier heater performance on a chilly NZ morning, and reduced wear on seals, oil, and emission controls. Once the engine’s up to temp, the thermostat meters coolant to keep it consistent, so the Splash doesn’t see big temp swings in Aussie summer traffic.

As part of regular servicing, a thermostat doesn’t need attention every visit, but it’s smart to check for tell‑tales: slow warm‑up, fluctuating gauge, weak cabin heat, or a fan that runs too often. Modern engines can also flag a thermostat that’s stuck open with a fault for “coolant temp below thermostat regulating temperature” (often seen as codes like P0128).

Replacement is straightforward workshop fare: drain enough coolant to drop the level below the housing, remove the housing, swap the thermostat and seal, then refill with the correct Suzuki‑spec coolant mix (distilled water and long‑life coolant at the right ratio). Bleed the system properly so there’s no air trapped under the bonnet, then verify with a scan tool or gauge that it warms at a normal rate and holds steady. It’s good practice to renew the thermostat when doing major cooling jobs—radiator, water pump, or a full coolant service at higher kilometres—because the part is inexpensive compared with the labour to get back in there later.

• Typical symptoms of a failing Splash thermostat:
  • Heater blows cool at speed but warms at idle
  • Temp gauge hunts or sits low after a long drive
  • Overheating after a short run (stuck closed)
  • Fuel use creeps up and engine feels a bit sluggish

Use quality OEM‑equivalent parts, a fresh gasket or O‑ring, and the correct torque on housing bolts. A tidy job and the right coolant will keep the Splash happy for many more kilometres.

Popular questions about the 2025 Suzuki Splash thermostat

Where is the thermostat located on a 2025 Suzuki Splash?

On Splash models with K10B/K12B petrol engines, the thermostat is typically housed in an alloy or plastic outlet where the lower radiator hose meets the engine block. It’s mounted at the front/side of the engine for easy hose routing.

On the 1.3 DDiS diesel, it’s also near the radiator hose junction on the engine side. Access often requires removing the intake ducting and shifting the hose clamp to reach the housing bolts cleanly.

How often should the thermostat be replaced?

There’s no fixed interval, it’s condition‑based. Many owners replace it preventively around major cooling work or past 120–160,000 kilometres, or at the first hint of slow warm‑up or temp instability.

If the coolant is overdue or contaminated, or if a pump and belt service is being done, replacing the thermostat and seal at the same time is a smart, low‑cost add‑on.

What are the signs the Splash thermostat is stuck?

Stuck open: long warm‑up, low heater output at highway speeds, and possible fault codes for low operating temperature. Stuck closed: overheating within minutes, hard upper radiator hose, and boiling in the expansion tank.

Either way, stop driving if temps spike. Cooling‑system damage from overheating costs a lot more than a quick thermostat swap and coolant refill.