Coolant Hose Flange – 2Q0 122 291K (OE)

Description

The 2Q0 122 291K Coolant Hose Flange is a Genuine OE-spec Radiator Coolant Hose Adapter for the left-side 2.0T inlet position in the primary cooling circuit. Specifically, this adapter provides the sealed, elbow/T-piece junction where the upper and/or lower radiator coolant hose connects to the water pump housing on MQB-B and MLB-evo platform vehicles. Furthermore, this part ships complete with its retaining C-clip and sealing O-ring, so the full junction assembly replaces in one step without sourcing separate hardware. Because the 2Q0 122 291K directly supersedes 5QN 122 291F, it is the current OE reference for all applications that previously specified the earlier part number. Additionally, multiple production-date variants exist within the same model year — specifically, build dates before 05/31/2019, from 06/01/2019, and from 08/23/2021 all carry distinct position notes. Therefore, always confirm the exact application by VIN before ordering.

Over time, the original plastic body of the 2Q0 122 291K Coolant Hose Flange weathers from sustained 2.0T operating temperatures, system pressure, and vibration at the left-side water pump housing. In particular, the elbow or T-piece geometry concentrates stress at the bend and at the C-clip engagement groove during each heat-and-pressure cycle. Consequently, hairline cracks can develop along the adapter walls or at the hose barb, while the O-ring can harden and lose compression at the sealing face. As a result, coolant begins to seep at the water pump housing junction, causing gradual coolant loss, recurring low-coolant warnings, and — if left unaddressed — progressive engine overheating. Therefore, replacing the failing 2Q0 122 291K promptly restores a factory-correct, pressurized, leak-free connection at the left-side coolant inlet.

Signs Your Coolant Hose Flange Needs Replacing

Catching a failing 2Q0 122 291K early prevents escalating cooling system damage. Therefore, watch for these warning signs:

• Coolant seeping or leaving dried residue at the left-side water pump housing junction or along the upper/lower radiator hose coupling

• Recurring low coolant level warnings despite topping off the reservoir, with no other obvious leak source

• A sweet coolant odor from the engine bay — particularly from the left side near the water pump — after reaching normal operating temperature

• Visible cracking, crazing, or discoloration on the adapter body at the elbow, T-piece junction, or C-clip groove

• The radiator hose feeling loose at the adapter coupling or failing to lock firmly with the C-clip engaged

• Engine temperature climbing above normal, indicating reduced coolant flow through the inlet circuit

If any of these symptoms appear, replace the 2Q0 122 291K without delay. Additionally, pressure-test the cooling system after installation to confirm no adjacent junction is seeping before returning the vehicle to service.

2Q0 122 291K Coolant Hose Flange — Key Features

• OEM Reference: 2Q0 122 291K (Genuine OE-spec; supersedes 5QN 122 291F)

• Left-side 2.0T inlet radiator coolant hose adapter — elbow/T-piece configuration at water pump housing

• Supplied complete with retaining C-clip and sealing O-ring

• Precision-molded to OE wall thickness and C-clip engagement geometry

• Broad MQB-B/MLB-evo platform compatibility — VW Atlas, Atlas Cross Sport, GTI, Jetta GLI, Tiguan 2.0L; Audi Q3

• Production-date sensitive — multiple position variants exist within the same model year; confirm by VIN

• Direct-fit replacement — no modifications required

Service Notes for the 2Q0 122 291K Coolant Hose Flange

• First, confirm fitment by VIN and production date — pre/post 05/31/2019 and post 08/23/2021 build dates carry distinct position and inlet notes; always match precisely before installation

• Next, install the supplied C-clip and O-ring — never reuse the old hardware on a new adapter, as a worn O-ring will not maintain the required compression at the sealing face

• Also, inspect the upper and lower radiator hoses at the adapter coupling ends; replacing cracked or hardened hoses together with the flange is best practice on higher-mileage vehicles

• Then, verify the hose locks fully into the new adapter and the C-clip engages with a firm click before pressurizing the system

• Finally, refill with VW/Audi-approved G12++/G13 coolant and bleed the cooling system completely to eliminate air pockets before returning the vehicle to service

2Q0 122 291K Coolant Hose Flange — Compatibility & Applications

Always verify fitment by VIN before ordering. Multiple variants may exist within the same model year.

Cross Reference Numbers

• 2Q0 122 291K (current Genuine OE reference)

• 2Q0-122-291-K (alternate formatting)

• 5QN 122 291F (superseded by 2Q0 122 291K)

Additional information