Parts for your 2020 Nissan Serena-Thermostat

2020 Nissan Serena Thermostat — what it does and when to replace it

Based on Nissan’s technical literature for the C27 Serena — notably the Nissan C27 Serena Service Manual (CO – Cooling System, 2019–2020 editions), plus Nissan’s Electronic Parts Catalog listings for the MR20DD (2.0 petrol S-HYBRID) and HR12DE (1.2 petrol generator for e-POWER) engines — the 2020 Nissan Serena is fitted with a conventional wax‑pellet thermostat located in the water inlet housing. So yes, a thermostat is absolutely relevant and used on every 2020 Serena variant, managing coolant flow and engine temperature as designed by Nissan.

The thermostat’s job is to help the engine warm up quickly and then hold a steady operating temperature, typically in the mid‑80s to low‑90s °C range. By staying closed when the engine is cold, it speeds up warm‑up for better fuel economy and smoother running. Once hot, it opens to let coolant circulate through the radiator, preventing overheating. That stable temperature keeps emissions in check and ensures the Serena’s hybrid systems, heater performance, and overall drivability behave as they should in Aussie and Kiwi conditions.

• Common signs it’s failing: slow warm‑up or poor heater output (stuck open), temp spikes or overheating (stuck closed), fluctuating gauge, cooling fans running oddly, or a Check Engine Light with a code like P0128.
• Thermostats aren’t a routine “every X kilometres” item, but they’re often replaced when there’s any cooling system fault, after major overheating, or during bigger cooling system work.
• Always renew the thermostat seal/O‑ring and refill with the correct Nissan long‑life blue coolant (premix). Don’t mix coolant types.

Servicing tips for a 2020 Serena thermostat under the bonnet: let the engine cool completely, drain enough coolant to sit below the housing, swap the thermostat and O‑ring (note orientation), clean mating faces, then refill and bleed air carefully. Use a vacuum filler if available, run the heater on hot to purge air, and top up the reservoir after a short test drive. Follow the Nissan service manual for any model‑specific steps and torque specs.

To keep things sweet long term, check coolant level and condition periodically, stick to the coolant change interval in the owner’s manual, and inspect hoses and clamps for weeps. If the temp gauge isn’t behaving as usual — especially on colder mornings — get it checked before it turns into an overheating drama.

Do all 2020 Nissan Serena models (S‑HYBRID and e‑POWER) have a thermostat?

They do. Both the MR20DD petrol and the HR12DE generator engine specified for the 2020 Serena use a thermostat in the water inlet housing, as shown in Nissan’s C27 Serena Service Manual and parts catalogues.

What are the tell‑tale signs the thermostat needs replacing?

Slow warm‑up, weak cabin heat, a temp gauge that wanders, overheating under load, cooling fans acting strangely, or a fault code like P0128. Any of these are a good reason to test or replace the thermostat and refresh the coolant.

Which coolant should be used, and how much does it take?

Use Nissan Genuine long‑life blue coolant (premix) or an equivalent that meets Nissan specs. Capacity varies by engine and configuration, so check the owner’s manual or service data for exact litres, as a ballpark, expect roughly 6–7 litres for a full system refill. Never mix coolant types.