VW Engine Coolant Expansion Header Tank Reservoir Bottle 1K0121407A 1K0121407F

VW Engine Coolant Expansion Header Tank Reservoir Bottle 1K0121407A 1K0121407F

£21.99
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VW Engine Coolant Expansion Header Tank Reservoir Bottle 1K0121407A 1K0121407F

VW Engine Coolant Expansion Header Tank Reservoir Bottle 1K0121407A 1K0121407F

£21.99
THEPARTPILOT
PRECISION PARTS • CLEAR FITMENT • BUY RIGHT FIRST TIME
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25,000+ PARTS
Stocked on the shelf
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FITTING SERVICE
Subject to availability
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30 DAY WARRANTY
As stated on this listing
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INTERNATIONAL
Eligible eBay destinations
⚠️ CRITICAL FITMENT CHECK
CURRENT EBAY COMPATIBILITY: VW GOLF MK5 / GOLF V 1K1 • 2.0 GTI PETROL • 2004, 2005, 2006, 2007, 2008 & 2009
Engine codes currently declared by the listing: AXX • BWA • CAWB
Do not order from the words “Golf” or the registration year alone. Compare part number, tank shape, hose-neck positions, mounting points and electrical connector with the part already fitted to your vehicle.
VOLKSWAGEN APPLICATION • COOLING SYSTEM

VW GOLF MK5 COOLANT EXPANSION / HEADER TANK RESERVOIR

PART NUMBER: 1K0 121 407 A
ITEM DETAILS & SPECIFICS
Brand Volkswagen
Part Type Engine Coolant Expansion / Header Tank Reservoir
Manufacturer Part Number 1K0121407A / 1K0 121 407 A
Interchange Part Number 1K0121407A / 1K0-121-407-A
Superseded / Later Part Number 1K0121407F / 1K0 121 407 F — verify vehicle/VIN and physical layout before ordering
Primary Vehicle Volkswagen Golf Mk5 / Golf V
Primary Chassis 1K1
Confirmed Current eBay Years 2004 • 2005 • 2006 • 2007 • 2008 • 2009
Confirmed Current eBay Engine 2.0 GTI Petrol • 1984cc • 147kW / 200HP
Engine Codes AXX • BWA • CAWB
Drive Front Wheel Drive on the current eBay compatibility entry
Body Hatchback. Door count is not used as the reservoir identification method — match chassis, engine, part number and physical design.
Visible Construction Translucent moulded plastic reservoir body with blue pressure cap as photographed
Electrical Connection Coolant level-sensor electrical connector visible on reservoir — compare plug shape and pin arrangement before purchase
Colour Marking Translucent / off-white reservoir body • blue cap
Condition Pre-owned component. Cosmetic marks may be present. Please inspect all item photographs.
Included Reservoir and blue cap as photographed. Hoses, mounting hardware or other surrounding components are not included unless clearly shown.
Warranty 30 days as stated on the live listing
eBay Item Number 147493783015
VAT VAT Global Accounting / margin-scheme item. VAT is not separately itemised and no separately reclaimable VAT amount is shown for the goods.
ACTUAL ITEM PHOTOGRAPHS
These photographs are from this eBay item. Please use them to compare reservoir shape, hose connections, mounting points and connector layout.
VW 1K0121407A coolant expansion header tank actual item photo
THEPARTPILOT
Volkswagen coolant reservoir 1K0121407A connector and tank reference
THEPARTPILOT
VW Golf coolant expansion tank actual part photograph
THEPARTPILOT
VW engine coolant header tank actual item 1K0 121 407 A
THEPARTPILOT
PHOTO VERIFICATION NOTE: The reservoir design, translucent body, blue cap, hose-neck arrangement and electrical connection can be checked from the photographs. The moulded part number is not sufficiently legible in the supplied photos for us to rely on photography alone, so 1K0121407A must also be verified against your existing tank/VIN application before ordering.
REFERENCE VEHICLE — VW GOLF MK5 / GOLF V

The image below shows a 2008 Volkswagen Golf 1K GTI 5-door hatchback, which sits within the current Golf GTI fitment declared for this listing. It is a reference vehicle photograph only and is not the donor vehicle.

2008 Volkswagen Golf Mk5 1K GTI 5 door reference vehicle
Reference vehicle image: 2008 Volkswagen Golf 1K MY08 GTI 5-door hatchback. Public-domain image via Wikimedia Commons. Reference only.
📍 WHERE THE PART IS FITTED

The coolant expansion/header tank is mounted in the engine bay and forms part of the engine cooling circuit. It provides expansion volume as coolant heats and cools, provides a visible coolant-level reference/fill point, and incorporates the level-sensor connection on this tank design.

In the reference engine-bay image below: look for the translucent round reservoir with the blue cap in the upper-side area of the engine bay. Exact surrounding components vary by engine.
VW Golf Mk5 R32 engine bay coolant expansion reservoir location reference
Reference engine-bay image: 2007 Volkswagen Golf R32 Mk5. Photo: The Car Spy, CC BY 2.0 via Wikimedia Commons. The R32 is shown only to illustrate the reservoir's engine-bay location; layout varies between engines.
WHAT THIS PART DOES

During normal operation engine coolant expands as temperature rises and contracts as the cooling system cools. The expansion reservoir provides controlled space for that change in volume and provides the system's coolant level reference/fill point.

On this reservoir design the electrical connection is associated with coolant-level monitoring. The reservoir does not independently control engine temperature; it is one component within the complete cooling system.

POSSIBLE SYMPTOMS OF A DAMAGED / FAILING RESERVOIR
Coolant staining / dampness A crack, seam failure, cap-sealing issue or hose connection may allow coolant to escape.
Repeated coolant level drop May indicate a leak from the reservoir or another part of the cooling system.
Coolant smell Escaping hot coolant can produce a noticeable coolant smell in or around the engine bay.
Coolant-level warning Low coolant or a level-sensor / electrical issue may trigger a warning depending on vehicle specification.
Overheating risk Significant coolant loss can reduce cooling-system effectiveness and may contribute to overheating.
These symptoms can also be caused by hoses, radiator, water pump, thermostat housing, cap, heater matrix or other cooling-system faults. Diagnose the vehicle before replacing parts.
✓ WHY MATCHING THE FACTORY PART NUMBER MATTERS

Correct fitment is more than the outside shape of the bottle. Hose-neck position and diameter, mounting tabs, cap arrangement, electrical connector geometry and available engine-bay clearance all need to correspond with the vehicle. Matching 1K0121407A / the recognised later 1K0121407F family together with your vehicle details gives much greater confidence than ordering from the vehicle name alone.

PARTS COMPATIBILITY CHART
Highest-confidence current listing fitment: Golf Mk5 / Golf V 1K1 GTI, 2004–2009, 2.0 petrol, engine codes AXX/BWA/CAWB. Manufacturer catalogue information also confirms the A-to-F part-number family on certain later applications shown below.
Make / Model Chassis / Version Exact Confirmed Year(s) Engine / Notes Confidence
VW Golf Mk5 / Golf V GTI 1K1 • Hatchback • FWD 2004, 2005, 2006, 2007, 2008, 2009 2.0 petrol • 1984cc • 200HP • AXX / BWA / CAWB Current eBay compatibility
Volkswagen Golf Later Golf application 2010 Manufacturer catalogue lists 1K0121407F with 1K0121407A in the supersession family. Confirm trim/VIN. Manufacturer confirmed
Volkswagen Tiguan Application depends on trim/engine 2010 Manufacturer catalogue lists 1K0121407F with 1K0121407A in the supersession family. Confirm trim/VIN. Manufacturer confirmed
ADDITIONAL PART-FAMILY INFORMATION: Manufacturer catalogue data also associates Audi A3, Audi Q3 and Audi TT with the 1K0121407A / 1K0121407F family. We have intentionally not published guessed year ranges for those models because the public manufacturer part page does not provide a closed year range. Please ask us to verify the exact vehicle through eBay Messages before ordering for those applications.
⛔ DO NOT ORDER IF...
✘ Your existing reservoir has a different hose-neck layout.
✘ Your electrical connector shape or pin arrangement is different.
✘ The mounting tabs / locating points do not correspond with the photographs.
✘ You are relying only on “VW Golf” and the registration year without checking the part.
✘ Your old reservoir carries an unrelated part-number family.
✘ You are purchasing for a Golf Mk7 / 5G / MQB vehicle without a VIN or part-number confirmation.
Important: an existing tank marked 1K0121407F is not automatically a mismatch, because that number is associated with the 1K0121407A supersession family. Vehicle application must still be checked.
✅ BUY-RIGHT-FIRST-TIME CHECKLIST
Read the part number from your existing reservoir where possible.
Compare the overall reservoir shape with every item photograph above.
Compare each hose-neck location and direction.
Compare mounting tabs and fixing points.
Compare the coolant-level electrical connector.
Check your chassis, engine code and vehicle year against the compatibility chart.
If anything differs, contact ThePartPilot through eBay Messages before purchase.
🧰 FITTING GUIDE
SAFETY: Never remove a coolant pressure cap while the engine/cooling system is hot. Allow the vehicle to become fully cold before beginning work.

1. Park securely, switch the ignition off and allow the engine/cooling system to become completely cold.

2. Protect painted areas and position a suitable drain/catch tray. Remove or drain enough coolant so the level is below the reservoir connections.

3. Disconnect the coolant-level sensor electrical plug carefully. Do not pull directly on the wiring.

4. Release the reservoir hose clamps using suitable clamp pliers and carefully free each hose. Expect residual coolant.

5. Remove the reservoir retaining fastener(s) or release it from its mounting points. Fastener type can vary by engine/application.

6. Place the old and replacement reservoirs side by side. Compare every hose neck, mounting point, connector position and part-number family before installation.

7. Install the replacement tank. Refit hoses fully to their stops and correctly position the original clamps or suitable replacements.

8. Reconnect the electrical level-sensor plug and confirm it locks securely.

9. Refill only with the correct coolant specification for your specific VIN/engine and bleed the cooling system according to the appropriate vehicle procedure.

10. Inspect for leakage while the vehicle reaches normal operating condition. After the vehicle cools completely, recheck coolant level and inspect all disturbed connections again.

REQUIRED / USEFUL TOOLS
🛠 Hose-clamp pliers / suitable regular pliers 🛠 Suitable socket / Torx / driver set
🛠 Pick / trim tool for electrical connector where appropriate 🪣 Coolant-safe drain tray
🧴 Funnel / suitable filling equipment 🥽 Gloves and eye protection
💡 Workshop light ❄ Correct coolant specification for your VIN/engine
⏱ ESTIMATED REPAIR TIME & GARAGE LABOUR GUIDE
Typical planning allowance: 0.5–1.0 labour hour / approximately 30–60 minutes

This is a general planning estimate rather than a manufacturer flat-rate time. Access, engine type, seized clamps/fasteners, coolant draining and bleeding requirements can increase workshop time.

GARAGE RATE 30 MIN / 0.5 HR 60 MIN / 1.0 HR
£50/hour £25 £50
£60/hour £30 £60
£70/hour £35 £70
£80/hour £40 £80
£90/hour £45 £90
£100/hour £50 £100
£110/hour £55 £110
£120/hour £60 £120
£130/hour £65 £130
£150/hour £75 £150
Labour figures are simple estimates based on rate × 0.5–1.0 hour and exclude coolant, diagnostics, additional components, seized fasteners or other work.
🔧 FITTING SERVICE AVAILABLE

ThePartPilot also offers a fitting / repair service subject to workshop availability and vehicle requirements. Please contact us through eBay Messages to ask about availability before making travel arrangements.

📮 CHECK YOUR DELIVERY ADDRESS BEFORE PAYMENT

Please make sure the delivery address selected at eBay checkout is complete and correct. For transaction security we cannot simply redirect a parcel to a different address after purchase. If an incorrect address has been used, request cancellation through eBay as quickly as possible and repurchase using the correct checkout address where possible.

🌍 INTERNATIONAL DELIVERY

International orders can be handled through eBay's international shipping programme where this item, the buyer and destination are eligible. eBay is currently transitioning UK sellers from the Global Shipping Programme to eBay International Shipping, so the options and destinations displayed at checkout are the final authority.

CURRENT GSP EU ELIGIBLE MARKETS

Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain and Sweden.

CURRENT GSP NON-EU ELIGIBLE MARKETS

Antigua and Barbuda, Aruba, Australia, Bahamas, Bahrain, Bangladesh, Barbados, Belize, Bermuda, Bolivia, Brazil, Brunei Darussalam, Cambodia, Canada, Cayman Islands, Chile, China, Colombia, Costa Rica, Dominica, Dominican Republic, Ecuador, Egypt, El Salvador, French Guiana, Grenada, Guadeloupe, Guatemala, Guernsey, Honduras, Hong Kong, Iceland, Indonesia, Israel, Jamaica, Japan, Jersey, Jordan, Kuwait, Liechtenstein, Macau, Malaysia, Maldives, Martinique, Mexico, Monaco, Montserrat, New Zealand, Nicaragua, Norway, Oman, Pakistan, Panama, Paraguay, Peru, Philippines, Qatar, Reunion, Saint Kitts and Nevis, Saint Lucia, Saudi Arabia, Singapore, South Africa, South Korea, Sri Lanka, Switzerland, Taiwan, Thailand, Trinidad and Tobago, Turks & Caicos Island, UAE, Ukraine, Uruguay, USA and Vietnam.

International availability, import charges, programme eligibility, restricted items and destination coverage are controlled by eBay and can change. Always use the delivery options shown by eBay at checkout.
↩️ RETURNS & FITMENT RESPONSIBILITY

This listing provides photographs, part-number information and compatibility guidance specifically to help buyers order the correct component first time. Please complete the fitment checklist before installation.

Returns are handled in accordance with the return terms shown on the eBay listing and eBay policy. If a returned automotive part has been installed, damaged, altered, contaminated, returned incomplete or otherwise suffers a loss in value after receipt, any permitted refund deduction will only be applied where eBay policy allows it and only to reflect the actual loss in value.

If the item you receive materially differs from the item described or photographed, please use the appropriate eBay return process and contact us through eBay Messages.

VAT GLOBAL ACCOUNTING / MARGIN SCHEME

This qualifying pre-owned item is sold under the applicable VAT Global Accounting / margin-scheme treatment. VAT is not separately itemised and there is no separately reclaimable VAT amount shown for the goods.

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Thank you for supporting ThePartPilot and a local independent automotive parts business. Keeping serviceable automotive components in circulation can reduce unnecessary waste, extend the useful life of existing parts and offer a cost-effective alternative to replacing every component with a newly manufactured one.

Pre-owned factory-numbered components can often represent a substantial saving compared with buying a newly supplied replacement, although the exact saving depends on the individual part and current market price. Our priority is simple: clear information, accurate matching and helping you buy the correct part first time.

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Scan the QR code to contact ThePartPilot on WhatsApp for fitment checks, appointments or fitting service availability.       
      
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