{"product_id":"x-autohaux-coolant-radiator-reservoir-tank-for-audi-a3-8va-8vf-5q0121407a-direct-fit-with-cap-2-pin-sensor","title":"X AUTOHAUX Coolant Radiator Reservoir Tank for Audi A3 8VA\/8VF — 5Q0121407A Direct-Fit with Cap \u0026 2-Pin Sensor","description":"\u003cstrong\u003eX AUTOHAUX coolant radiator reservoir tank (part 5Q0121407A) is a direct-fit replacement expansion tank with cap and 2-pin sensor for select Audi, Volkswagen and SEAT models from 2012–2020.\u003c\/strong\u003e\n\n\u003cp\u003eThis replacement coolant reservoir restores the coolant storage and overflow functions of the cooling system, keeping working temperatures stable and helping prevent heat-related drivability issues. Manufactured to match OE fitment and mounting points, the tank accepts the cap and the two-pin sensor included, making it a straightforward option when the original plastic reservoir has cracked, leaked, or become discolored.\u003c\/p\u003e\n\n\u003ch3\u003eWhich vehicles will this tank fit?\u003c\/h3\u003e\n\u003cp\u003eThe part is designed for a broad set of VW Group vehicles from mid-2010s platforms. Check the part numbers and model years against your VIN to confirm compatibility before ordering.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003ePart numbers covered: 5Q0121407A, 5Q0121407D, 5Q0121407G.\u003c\/li\u003e\n  \u003cli\u003eCompatible models include Audi A3 8VA\/8VF (2012–2020), Audi Q2 GAB (2016–2020), Audi Q3 F3 (2018–2020), Audi TT MK3 FV (2014–2020).\u003c\/li\u003e\n  \u003cli\u003eAlso fits Volkswagen Golf MK7 (2012–2020), Volkswagen Arteon 3H7 (2017–2020), Volkswagen Passat 3G (2014–2020), and Seat Ateca KH (2016–2020).\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does this replacement reservoir perform compared with the original?\u003c\/h3\u003e\n\u003cp\u003eBuilt from reinforced plastic and treated to resist corrosion, the X AUTOHAUX tank aims to match the durability and sealing properties of the factory unit. It includes the filler cap and a two-pin sensor interface so you retain coolant-level monitoring and pressure control functions.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDurable material resists oxidation and deformation over time.\u003c\/li\u003e\n  \u003cli\u003eSeals and mounting points machined to match original geometry for a snug fit.\u003c\/li\u003e\n  \u003cli\u003eIncludes cap and 2-pin sensor connection to preserve instrumentation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat’s involved in replacing the coolant reservoir?\u003c\/h3\u003e\n\u003cp\u003eReplacement is a moderate DIY task that requires basic hand tools and a clean drain pan. Always let the engine cool completely, then relieve any residual pressure before disconnecting hoses or removing mounting bolts to avoid spills.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eTurn off engine and allow to cool fully before starting work.\u003c\/li\u003e\n  \u003cli\u003eRemove mounting fasteners, drain or catch remaining coolant, and detach hoses carefully.\u003c\/li\u003e\n  \u003cli\u003eInstall new tank, reconnect hoses and sensor, tighten clamps, and refill coolant to the specified level.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWill installing this tank fix overheating issues?\u003c\/h3\u003e\n\u003cp\u003eReplacing a cracked or leaking reservoir eliminates coolant loss from the expansion system, which can be a cause of overheating and erratic engine temperature readings. However, overheating can have other causes—thermostat, water pump, radiator, or head gasket—so inspect the entire cooling system if problems persist.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eStops coolant leaks from a damaged overflow\/reservoir tank.\u003c\/li\u003e\n  \u003cli\u003eMaintains correct coolant volume and pressure behavior under normal operation.\u003c\/li\u003e\n  \u003cli\u003eIf overheating continues, further cooling-system diagnostics are recommended.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: This X AUTOHAUX reservoir tank is intended for owners and technicians servicing mid-2010s Audi, Volkswagen and SEAT models who need an OE-form replacement with cap and sensor. It suits DIY mechanics replacing a failed plastic expansion tank, independent shops performing cooling-system repairs, or fleet managers refreshing aging vehicles to prevent coolant loss and maintain reliable engine temperature control.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Does this tank include the cap and sensor?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes — the X AUTOHAUX reservoir comes with the filler cap and the 2-pin sensor installed for ready fitment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I install this myself?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes; basic tools and coolant capture are needed. Let the engine cool and follow the vehicle service steps for safe installation.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"X AUTOHAUX","offers":[{"title":"Default Title","offer_id":67591808843961,"sku":"B0C53PSN48","price":78.6,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0822\/3765\/3177\/files\/x-autoHaux-front-view-reservoir-tank.jpg?v=1790558648","url":"https:\/\/redleafauto.ca\/products\/x-autohaux-coolant-radiator-reservoir-tank-for-audi-a3-8va-8vf-5q0121407a-direct-fit-with-cap-2-pin-sensor","provider":"Redleaf Auto","version":"1.0","type":"link"}