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Details
| Specification | Value |
|---|---|
| Brand | HART |
OE/OEM numbers (1)
Search by this OE number to find compatible parts
- AUDI / SEAT / SKODA / VW—4D0 905 351
Where this part fits
Original-fit position for OE 4D0905351. The red ring marks where this part installs on the vehicle.
About this product
Sourced from HART, this switch unit ignition system (521 387) combines precision engineering with durable materials to meet the demands of everyday driving and extended service intervals. Verified to fit AUDI, SEAT, SKODA, VW models. All compatibility data is cross-checked against the TecDoc database — select your vehicle to confirm the part matches your specific engine and year. This part supersedes original equipment references: 4D0 905 351. Matching these numbers confirms a like-for-like replacement with no loss of function. HART is a recognised supplier of automotive ignition components to independent workshops and dealer networks across Europe. All parts are sourced from authorised distribution channels and carry full manufacturer traceability — you receive exactly the same component supplied to professional garages and dealer workshops. If fitment or specifications do not match your vehicle, our technical team can help identify the correct alternative — use the vehicle selector or contact us with your VIN for a guaranteed-fit recommendation. Replacing worn components on schedule preserves your vehicle's safety, reliability, and resale value — and aftermarket parts from established brands deliver OEM-equivalent performance at a fraction of the dealer price. Every part is dispatched from our UK warehouse with a 30-day money-back guarantee and free hassle-free returns.
Suitable cars
No equivalent parts found.
Switch Unit Ignition System HART 521 387 — compatible car models
| Car models | AUDI: A3 (8L1), A4 B5 (8D2), A4 B5 Avant (8D5), A4 B6 (8E2), A4 B6 Avant (8E5), A6 C4 (4A2), A6 C4 Avant (4A5), A6 C5 (4B2, 4B4), A6 C5 Avant (4B5, 4B6), A8 D2 (4D2, 4D8); SEAT: ALHAMBRA (7V8, 7V9), LEON (1M1); SKODA: OCTAVIA I (1U2), OCTAVIA I Combi (1U5); VW: BORA I (1J2), BORA Variant (1J6), GOLF IV (1J1), GOLF IV Variant (1J5), NEW BEETLE (9C1, 1C1), NEW BEETLE Convertible (1Y7), PASSAT B5 (3B2), PASSAT B5 Variant (3B5), SHARAN (7M8, 7M9, 7M6) |
|---|---|
| Engines | 1.8 T; S6 Plus quattro; 3.7; 1.8 T 20V; 1.8 20V T |
| Year of manufacture | 1994-2013 |
| Manufacturer article number (MPN) | 521 387 |
| OE part numbers | 4D0 905 351 |
Compatibility check
Loading vehicle data…
Please wait while we load vehicle compatibility information.Description and what's included
HART 521387 . 521 387
- 1x Switch Unit Ignition System
Shipping, returns, warranty
Free UK delivery on orders over £99.00. Express and standard shipping available.
- Standard delivery: 2-5 business days
- Express delivery: 1-2 business days
- Free returns within 14 days
- All parts backed by manufacturer warranty
Warranty: 12-month manufacturer warranty on all parts. 14-day money-back guarantee if the part doesn't fit your vehicle.
Frequently Asked Questions
Is this Switch Unit Ignition System compatible with my car?
This Switch Unit Ignition System fits AUDI, SEAT, SKODA, VW vehicles. Use the vehicle selector at the top of the page to check exact compatibility — enter your car's make, model, and engine for a confirmed fitment match. All fitment data is verified through TecDoc.
What specifications does this HART Switch Unit Ignition System have?
The package includes the Switch Unit Ignition System as described in the specifications above. Check the "What's included" section for a full list of components. If mounting hardware or accessories are required, they will be listed separately.
What OE part numbers does this Switch Unit Ignition System replace?
This Switch Unit Ignition System replaces OE part numbers: 4D0 905 351. Cross-reference these numbers with your vehicle's original part number to confirm compatibility.
How much does a Switch Unit Ignition System cost?
This HART Switch Unit Ignition System is available for £25.99. Switch Unit Ignition System prices vary depending on brand, specifications, and vehicle compatibility. HART parts offer a balance of quality and value, backed by our 14-day money-back guarantee.
How do I know when to replace my Switch Unit Ignition System?
Regular inspection of your Switch Unit Ignition System is recommended as part of routine vehicle maintenance. Watch for changes in performance, unusual noises, or visual signs of wear. Consult your vehicle's owner manual for manufacturer-recommended replacement intervals specific to your make and model.
What tools do I need to replace a Switch Unit Ignition System?
Tools required vary by vehicle make and model. Generally, a basic socket set, screwdrivers, and vehicle-specific tools may be needed. We recommend consulting a workshop manual for your specific vehicle, or having the Switch Unit Ignition System fitted by a professional mechanic.
Can I use this part as a replacement for OE 4D0 905 351?
Yes, this HART Switch Unit Ignition System is a direct replacement for OE part number 4D0 905 351. It is manufactured to meet or exceed original equipment specifications, ensuring proper fitment and performance. All cross-reference data is verified through TecDoc.
Related categories
Common OE numbers for this part
Common original equipment numbers linked to stocked alternatives.
