X4XZ Coolant Reservoir with Sensor for BMW 120i–520i (2012–2019) — OEM-fit replacement, durable plastic

The X4XZ 603-880 coolant reservoir with integrated sensor replaces OEM overflow tanks to restore proper coolant expansion control and level monitoring on compatible 2012–2019 BMW 120i–520i models.

If your BMW is showing low-coolant warnings, coolant loss, or visible cracks in the original surge tank, swapping in a correctly sized replacement reservoir can prevent overheating symptoms and maintain stable engine temperature during normal driving. This X4XZ unit is built to match the fitment and connector locations for the listed BMW F-series engines and includes the sensor mounting to interface with the vehicle's level monitor.

Which BMW models will this reservoir fit?

This tank is specified for multiple 2012–2019 BMW variants with 2.0L inline‑4 engines across F20, F22, F23, F30, F31, F32, F33, F34 and F36 chassis codes. Check your OEM part number against 603-880 or replacement references 17137642158 and 17137609469 to confirm compatibility.

• Fits 120i, 220i, 228i, 320i, 328i, 420i, 428i and 520i models listed in the product spec.
• Covers both xDrive and rear-wheel-drive variants where noted.
• Intended for vehicles originally equipped with the matching sensor port and cap style.

How is this replacement built and what does it include?

The reservoir is molded from durable automotive-grade plastic and factory-tested for fit. It comes as a single complete surge tank ready to install; the cap and sensor mounting area match the OEM layout for straightforward replacement.

• Includes one coolant reservoir tank (cap and sensor connectors accommodated).
• Manufactured to resist common wear like cracking and coolant exposure.
• OE reference 603-880; replacement numbers supplied for cross-checking.

What should I expect during installation and maintenance?

Installation is generally a moderate DIY job or quick for a professional shop: drain or recover coolant, remove the old tank and sensor, fit the new reservoir, reconnect hoses and sensor electricals, then refill and bleed the system as required. No instruction manual is included, so consult a repair guide or service manual for your specific model.

• Prepare by recovering coolant and protecting nearby components from spills.
• Verify sensor connection and hose clamps are secure before refill.
• Perform coolant bleed procedure to remove trapped air after installation.

What after-sales support comes with the part?

X4XZ provides customer service and a one-year product support window for installation or quality concerns. If you encounter fitment or function issues, contact the seller for troubleshooting and warranty assistance.

• 24-hour customer support available for questions and guidance.
• One-year product service covering manufacturing defects under normal use.
• Keep purchase details and vehicle info handy when contacting support.

Who is this for: This replacement is aimed at BMW owners, mechanics, and independent repair shops who need a direct-fit coolant overflow reservoir for the listed 2012–2019 2.0L BMW models. Choose this X4XZ tank if your original surge tank is cracked, leaking, or triggering coolant-level warnings and you want a like-for-like unit that matches OEM mounting points and sensor accommodation. If you are unsure about compatibility, verify your vehicle's part number or consult a professional prior to purchase.