X4XZ Coolant Overflow Reservoir with Sensor for 2012–2019 BMW 120i–520i | Complete Tank, Cap Included

Replacement coolant overflow reservoir with integrated sensor designed to restore proper coolant level monitoring and expansion capacity on select 2012–2019 BMW 120i through 520i models.

When an aging or cracked surge tank causes coolant loss, dashboard warnings, or cooling-system imbalance, fitment of a correctly matched reservoir brings back reliable coolant expansion capacity and sensor feedback. The X4XZ 603-880 reservoir is molded and tested to match the specified BMW applications and replaces OE numbers 17137642158 and 17137609469. It ships as a complete tank with cap and sensor-ready connections so you can restore coolant containment and level detection without guessing on compatibility.

Which BMW models will this reservoir fit?

This tank is engineered for a range of BMW 2-, 3-, 4- and 5-series cars with 2.0L four-cylinder engines produced between 2012 and 2019. Confirm your VIN and engine code against the listed applications before ordering to ensure a direct fit.

• Compatible models include: 120i (F20), 220i/228i (F22/F23), 320i/320i xDrive/328i (F30/F31), 420i/428i variants (F32/F33/F36), and 520i (F10/F18 similar years).
• Replaces OE numbers: 17137642158 and 17137609469.
• Fits 2.0L L4 engines from model years 2012–2019 where listed.

How does this reservoir help my cooling system perform?

The reservoir provides a dedicated expansion space for coolant as temperatures change, preventing air entry and maintaining appropriate radiator pressure cycles. Its sensor-ready design restores accurate level monitoring so warning lights and ECU inputs behave correctly.

• Contains expansion and contraction of coolant during heat cycles.
• Prevents overflow and coolant loss from a failing tank.
• Supports level sensor function to keep dashboard indicators accurate.

What are the build quality and included parts?

This replacement reservoir is made from durable automotive-grade plastic and is produced to meet fitment and durability expectations for the specified BMW models. The package includes a complete coolant reservoir; mounting hardware and cap are included as fitted to the tank, but no printed manual is provided.

• Durable molded plastic construction designed for long service life.
• Factory-style connections for hoses and level sensor port.
• Package includes 1 coolant reservoir; easy to install for technicians and DIYers.

How do I install it and what after-sales support is available?

Installation is straightforward for anyone familiar with basic cooling-system service: drain coolant to safe level, disconnect hoses and electrical connector, remove old tank, install new reservoir and refill with correct coolant. X4XZ offers customer support and a one-year product service if you encounter fitment or quality issues.

• Simple swap procedure for competent DIY mechanics or professional shops.
• Always refill with manufacturer-recommended coolant and bleed air per BMW procedure.
• X4XZ provides 24-hour customer service and a one-year product warranty.

Who is this for: drivers and mechanics who own compatible BMW 120i, 220i, 228i, 320i, 328i, 420i, 428i or 520i models from 2012–2019 and need a direct-fit replacement for a leaking, cracked, or sensor-failing coolant reservoir. Choose this tank when you want an OE-replacement part number match (603-880 / 17137642158 / 17137609469) with durable construction and responsive after-sales support to return cooling-system function quickly and reliably.