--- product_id: 806424043 title: "Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue)" brand: "bawkars" price: "$17.29" currency: USD in_stock: true category: "Bawkars" url: https://www.desertcart.us/products/806424043-coolant-reservoir-tank-cap-4m0121321e-coolant-recovery-surge-tank-cap store_origin: US region: United States of America --- # Quick hand-install Secure pressure seal OEM 4M0121321E exact fit Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) **Brand:** bawkars **Price:** $17.29 **Availability:** ✅ In Stock ## Summary > 💙 Keep your engine cool, your ride sharp, and your maintenance stress-free! ## Quick Answers - **What is this?** Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) by bawkars - **How much does it cost?** $17.29 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/806424043-coolant-reservoir-tank-cap-4m0121321e-coolant-recovery-surge-tank-cap) ## Best For - bawkars enthusiasts ## Why This Product - Trusted bawkars brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Pressure-Perfect Seal:** Maintains optimal cooling system pressure to prevent costly engine overheating. - • **Durable Underhood Armor:** Built tough to withstand extreme engine bay conditions for long-lasting reliability. - • **Effortless DIY Installation:** Hand-tightens in seconds—no tools, no hassle, zero downtime. - • **Precision OEM Compatibility:** Seamlessly fits Volkswagen, Audi & Porsche models for flawless replacement. - • **Vibrant Blue Identification:** Striking blue cap ensures quick visual checks and adds a subtle style upgrade. ## Overview This Coolant Reservoir Tank Cap (OEM 4M0121321E) is a direct replacement designed for Volkswagen, Audi, and Porsche models. Engineered with durable automotive-grade plastic, it ensures a secure pressure seal to optimize engine cooling performance. Featuring a vibrant blue finish for easy identification and a quick hand-tight installation, it’s the perfect upgrade for proactive vehicle maintenance and reliable daily driving. ## Description Product Item:​Coolant Reservoir Tank CapUniversal Fit For:​● Volkswagen models​ Audi PorscheOEM:​● OE number 4M0121321E​Features:​▲ Blue color for easy identification​▲ Functions as coolant reservoir tank cap and radiator cap​▲ Sturdy construction for underhood durability​▲ OE matching design for reliable performance​▲ Works as audi radiator cap and coolant cap replacement​▲ Secure pressure retention design​Function:​✔ Maintains proper cooling system pressure​✔ Replaces worn or damaged radiator reservoir cap​✔ Prevents pressure loss for efficient cooling​✔ Works as water tanks cap to protect cooling components​✔ Ensures consistent performance in diverse driving conditions​Specification:​□ Color: Blue​□ OE Number: 4M0121321E​□ Type: Coolant reservoir tank cap□ Material: Automotive grade plastic​□ Compatibility: Volkswagen Audi Porsche models​□ Quantity: 1 PC​Easy Installation:​◆ Hand tightens for quick setup​◆ No tools or modifications required​◆ Fits standard coolant reservoir openings​◆ Direct replacement for old or faulty caps​◆ Secure fit with simple twist on design​◆ Takes minutes to install without expertise​Package Includes:​1 PC Coolant Reservoir Tank Cap ## Features - Precise Compatibility: This coolant reservoir tank cap fits Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche, serving as audi radiator cap for seamless replacement in compatible vehicles. - OEM Matching: This radiator cap replacement replaces OE number 4M0121321E, functioning as coolant cap that aligns with factory specifications for reliable performance in cooling systems. - Secure Seal: This radiator reservoir cap maintains system pressure, working as coolant reservoir cap replacement to support optimal engine cooling in compatible vehicles.​ - Durable Build: This coolant reservoir cap features sturdy construction that resists underhood conditions, acting as water tanks cap for long-lasting use in daily driving or trips. - Easy Installation: This blue radiator cap installs in seconds by hand, fitting standard reservoirs as hassle-free coolant reservoir tank cap for DIY maintenance. ## Images ![Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) - Image 1](https://m.media-amazon.com/images/I/61+qroIHV+L.jpg) ![Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) - Image 2](https://m.media-amazon.com/images/I/614JPrGD9JL.jpg) ![Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) - Image 3](https://m.media-amazon.com/images/I/617oK2sFQYL.jpg) ![Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) - Image 4](https://m.media-amazon.com/images/I/71H-ic7TRjL.jpg) ![Coolant Reservoir Tank Cap, 4M0121321E Coolant Recovery Surge Tank Cap, Compatible with Volkswagen Audi A4 A5 A6 A7 A8L S4 S5 Q5 Q7 Q8 RS4 RS5 Porsche (Blue) - Image 5](https://m.media-amazon.com/images/I/71RCij3iRfL.jpg) --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.us/products/806424043-coolant-reservoir-tank-cap-4m0121321e-coolant-recovery-surge-tank-cap](https://www.desertcart.us/products/806424043-coolant-reservoir-tank-cap-4m0121321e-coolant-recovery-surge-tank-cap) --- *Product available on Desertcart United States of America* *Store origin: US* *Last updated: 2026-07-08*