Parts for your 2019 Mitsubishi Asx-Heater hose

2019 Mitsubishi ASX heater hose — purpose, servicing and replacement

Technical documentation confirms the 2019 Mitsubishi ASX is fitted with heater hoses. Mitsubishi Motors’ ASX/RVR/Outlander Sport Workshop Manual (Group 55A: Heater, Air Conditioner and Ventilation) details the heater water hose routing between the engine and the heater core, and the Cooling System section (Group 14) specifies coolant flow through the heater circuit. The Mitsubishi ASA electronic parts catalogue for GA/GM series ASX also lists the heater water hose (inlet and outlet) assemblies and clamps. So, a heater hose is absolutely relevant on this model.

On the 2019 ASX, the heater hose carries hot engine coolant to and from the heater core under the dash. That hot coolant warms the cabin air for winter comfort and helps the windscreen demister clear fog quickly. Because it’s part of the engine’s cooling loop, hose condition also affects engine temperature stability.

• Purpose: move hot coolant from the cylinder head/outlet to the heater core and return it to the engine.
• Why it matters: reliable cabin heat and demisting, plus dependable coolant circulation under the bonnet.

For servicing, the hose should be inspected at every routine service interval (typically 10,000–15,000 kilometres in AU/NZ conditions). A technician will check for surface cracking, swelling near the clamps, soft spots, oil contamination, fraying fabric reinforcement, and any dried coolant traces around fittings at the firewall and thermostat housing.

1. Always work only when the engine is fully cool and system pressure is released.
2. Replace hoses as a pair (inlet and outlet) and fit new quality clamps, spring clamps are preferred for constant tension.
3. Use the correct moulded hose shapes and diameter to avoid kinks and chafe, route through factory clips and keep clear of sharp edges.
4. Refill with Mitsubishi-approved long-life coolant at the specified mix. Bleed air with the heater set to HOT, idle up to temperature, and top up the reservoir to the MAX mark after a short drive once cool.
5. Recheck for seepage under the bonnet and listen for gurgling (a sign of trapped air).

A practical replacement window is around 8–10 years or 160,000 km, sooner if the vehicle operates in high heat, tows frequently, or shows any of the warning signs. Common symptoms include a sweet coolant smell, dampness near the firewall, low coolant level, a rising temperature gauge, or coloured residue at hose ends.

Popular questions about the 2019 Mitsubishi ASX heater hose

What size heater hose does a 2019 ASX use?
Most ASX variants use hoses in the 16–19 mm internal diameter range, but the factory hoses are moulded pieces with specific bends and lengths. The correct size and shape should be confirmed against the VIN in the Mitsubishi parts catalogue or measured at the engine and firewall barbs to ensure a snug, leak-free fit.

Can a universal straight hose be used instead of the moulded ASX heater hose?
Short straight sections may work in a pinch, but the ASX typically needs moulded bends to clear components and prevent kinking. For longevity and proper routing under the bonnet, a moulded EPDM coolant-rated hose is the safer choice. If a universal hose is used, ensure no flattening on tight bends and protect any areas that could chafe.

How should air be bled after replacing the ASX heater hose?
Refill the system with the correct coolant, set the HVAC to HOT, and run the engine at fast idle until the radiator fan cycles. Squeeze the upper radiator hose a few times to encourage bubbles out, top the reservoir to MAX, then allow a full cool-down and recheck the level. Some engines include a bleed point, if fitted, follow the workshop manual procedure.