Parts for your 2017 Mitsubishi Outlander-Thermostat housing

2017 Mitsubishi Outlander thermostat housing — what it is, what it does, and when to replace it

Yes, the 2017 Mitsubishi Outlander does use a thermostat housing. Technical sources including the Mitsubishi Outlander (GF/GM) Workshop Manual (Cooling System – Thermostat/Water Inlet) and the Mitsubishi ASA/EPC parts catalogue list a dedicated thermostat and housing (often called the “thermostat case” or “water inlet/outlet”) across the 2.0 and 2.4 petrol, diesel, and PHEV variants. Independent repair data platforms such as Autodata and Mitchell1 also document servicing procedures for the Outlander’s thermostat and housing for this model year.

On the 2017 Outlander, the thermostat housing is the physical body that holds the thermostat in place and routes coolant between the engine and radiator. Its job is simple but vital: help the engine reach operating temperature quickly, then keep it there by regulating coolant flow. The housing typically carries the thermostat, an O-ring or gasket, hose stubs, and sometimes sensor ports. Most Outlanders from this era use a composite (plastic) housing that’s light and efficient but can eventually age, warp, or crack, especially if coolant changes are skipped or the engine has overheated.

It’s not a routine replacement item, but it’s smart to keep an eye on it during services. Tell-tale signs it’s on the way out include pink/green/blue crust around the housing, a sweet coolant smell, slow warm-up or over-cooling (often setting a P0128 code), overheating, or visible leaks where the hoses and housing meet.

• Use the correct coolant: Mitsubishi Genuine Super Long Life Coolant (blue) or an equivalent that meets Mitsubishi specs. Stick to a proper 50/50 premix unless otherwise specified.
• If the thermostat is being replaced, always fit a new O-ring/gasket and clean the mating surfaces. Don’t over-tighten the housing bolts, follow workshop torque specs.
• Bleed the cooling system thoroughly. Run the heater on hot, top up as required, and check for air pockets and stable operating temp.
• Consider preventative replacement of the thermostat and housing together if there’s evidence of ageing plastic, repeat P0128 faults, or you’re already doing major cooling system work.

1. Allow the engine to cool completely.
2. Drain enough coolant to drop the level below the housing.
3. Remove intake ducting or covers for access, then hoses and mounting bolts.
4. Swap in the new thermostat and housing, orienting any jiggle valve as per the manual.
5. Refit, torque to spec, refill coolant, bleed, and road test while watching temps and for leaks.

A careful check at each service and timely replacement when symptoms show will keep the Outlander running sweet and protect the head gasket and radiator from grief.

Popular questions

Where is the thermostat housing on a 2017 Outlander?
It’s mounted low on the engine at the water inlet/outlet, where the lower radiator hose connects. Access can vary by engine (2.0, 2.4, diesel, or PHEV), and some intake ducting or covers may need to be moved for room to work.

What symptoms point to a bad thermostat or housing?
Coolant leaks around the housing, overheating, slow warm-up or over-cooling (often with a P0128 code), poor cabin heat, and a sweet coolant smell. Any of these warrant an inspection before bigger problems crop up.

Are PHEV and diesel thermostat housings the same as petrol models?
No. While the function’s the same, the parts and locations can differ between petrol, diesel, and PHEV due to packaging and cooling circuit differences. Match parts to the exact engine code and VIN.