Parts for your 2015 Mitsubishi Asx-Thermostat

2015 Mitsubishi ASX Thermostat – purpose, care and when to replace

Technical sources confirm the 2015 Mitsubishi ASX is fitted with a conventional engine coolant thermostat. The Mitsubishi Motors ASX/RVR/Outlander Sport workshop manual for GA/GA2W/GA3W series, the Mitsubishi ASA parts catalogue, and common service data (e.g., Autodata) all specify a wax‑type thermostat mounted in the water inlet housing on both petrol (4B-series) and diesel (4N-series) engines. So yes—this part is absolutely relevant to the 2015 ASX.

The thermostat’s job is to get the engine up to operating temperature quickly and then keep it there. It stays closed when cold to speed warm‑up, then opens progressively (typically beginning around the low‑to‑mid 80s °C and fully open in the 90s °C) to circulate coolant through the radiator. That means better fuel economy, smoother running, steadier cabin heat, and lower emissions. If it sticks shut, the ASX can overheat, if it sticks open, it’ll run cool, chew more fuel, and set a fault like P0128.

While the thermostat isn’t usually a “replace every service” item, it’s smart to check it whenever the cooling system is being worked on or coolant is changed as per the service schedule. Owners often choose to replace it pre‑emptively at higher kilometres or when doing related jobs like a water pump or radiator service. Using the correct spec thermostat and a new O‑ring/gasket is key, and the cooling system should be refilled with the correct Mitsubishi‑approved long‑life coolant and bled properly to avoid air pockets.

Common clues that the ASX needs a thermostat are a temp gauge that can’t make up its mind, slow warm‑up and weak heater on cold mornings, overheating under load, fans running more than normal, or fault codes about coolant temperature. If any of that pops up, it’s time for a proper cooling system check rather than guessing parts.

• When to replace: overheating or running cool, fluctuating gauge, P0128, during major cooling system work, or at high km in harsh climates.
• Fitment tips: work on a cold engine, drain enough coolant to drop the level, note orientation (jiggle pin up, where applicable), torque the housing evenly, refill with the right coolant, bleed thoroughly, check for leaks under the bonnet after a short road test.

FAQs

What temperature does the 2015 ASX thermostat open?
Depending on engine variant, it typically begins to open around the low‑to‑mid 80s °C and is fully open in the 90s °C range. That balance helps quick warm‑up without risking overheating. Always match the replacement to the engine code and OEM spec.

Where is the thermostat on a 2015 Mitsubishi ASX?
It’s housed in the water inlet at the engine end of the lower radiator hose. On petrol models it’s usually at the front of the engine near the drive belts, on the diesel it’s in a similar lower‑hose housing near the block. Access varies a bit by engine and accessories.

What are signs the thermostat has failed on an ASX?
Overheating, slow warm‑up, poor cabin heat, a temp gauge that swings about, radiator hoses not warming evenly, or a P0128 code. Any of these warrant a cooling system inspection and likely thermostat testing or replacement.