The Volkswagen BAG is a 1,781 cc, inline‑four naturally aspirated petrol engine produced between 2000 and 2008. It features a cast iron block, aluminium head, double overhead camshafts (DOHC), and 20 valves. This unit, part of the EA113 family, delivered 92 kW (125 PS) and 170 Nm of torque, providing smooth, linear power delivery characteristic of its era.
Fitted primarily to the Mk4 Golf, B5 Passat, and SEAT Toledo, the BAG was engineered for dependable daily commuting an…
Volkswagen
Production years 2000–2005 meet Euro 3 standards; 2006–2008 models meet Euro 4 (VCA UK Type Approval #VCA/EMS/8891).
The Volkswagen BAG is a 1,781 cc inline‑four naturally aspirated petrol engine engineered for compact and mid-size sedans/hatchbacks (2000-2008). It combines DOHC 20-valve architecture with a variable intake manifold to deliver smooth, linear power and good fuel efficiency. Designed to meet Euro 3 and Euro 4 standards, it offers a blend of reliability and cost-effective motoring.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,781 cc | |
Fuel type | Petrol | |
Configuration | Inline‑4, DOHC, 20‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 81.0 mm × 86.4 mm | |
Power output | 92 kW (125 PS) @ 5,700 rpm | |
Torque | 170 Nm @ 4,200 rpm | |
Fuel system | Bosch Motronic ME 7.5, multi-point injection | |
Emissions standard | Euro 3 (2000–2005); Euro 4 (2006–2008) | |
Compression ratio | 10.8:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Toothed belt | |
Oil type | VW 502 00 (SAE 5W‑40) | |
Dry weight | 125 kg |
The Volkswagen BAG was used across Volkswagen's A4 and B5 platforms with transverse mounting. This engine received platform-specific adaptations-reinforced engine mounts in the Passat and a unique air intake duct for the Golf. All adaptations are documented in OEM technical bulletins.
The BAG's primary reliability risk is coolant loss from the failing plastic flange, with elevated incidence in high-mileage vehicles. Volkswagen TSB 2017890 documents this as a widespread service item, while owner reports frequently cite overheating incidents. Neglecting this simple repair can lead to warped cylinder heads or complete engine failure, making proactive replacement critical.
Analysis derived from Volkswagen technical bulletins (2000-2008) and aggregated owner repair data. Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The BAG engine is generally very reliable if its two main weaknesses are addressed: the plastic coolant flange and the timing belt. Proactively replacing the flange with the metal version and adhering to the 90,000 km timing belt interval can result in trouble-free operation beyond 250,000 km. Neglecting either item can lead to expensive repairs.
The most common and critical problems are coolant flange failure and timing belt failure. Secondary issues include ignition coil failures and, in poorly maintained examples, oil sludge buildup. These are well-documented in Volkswagen service bulletins, with the coolant flange being the most frequent and easily preventable failure.
The BAG engine was primarily used in the Mk4 Golf (2000-2006), B5 Passat (2000-2005), and was also found in the SEAT Toledo (2000-2004) and Škoda Octavia (2001-2004). It was the 1.8 20V variant for these specific applications.
Yes, the BAG responds well to tuning. A simple ECU remap can yield gains of 15-25 kW. With supporting modifications like a performance exhaust and intake, outputs of 110-120 kW are achievable. The bottom end is robust, but ensuring the cooling system (especially the flange) is in perfect condition is crucial before any tuning.
Fuel economy is respectable for its time. Expect around 9.5 L/100km (30 mpg UK) in city driving and 6.5 L/100km (43 mpg UK) on the highway for a Golf. The heavier Passat will be slightly thirstier, averaging around 10.0 L/100km (28 mpg UK) combined in mixed driving conditions.
Yes. The BAG is an interference engine. If the timing belt fails, the pistons will collide with the open valves, causing severe and expensive internal damage. This makes adhering to the timing belt replacement schedule non-negotiable for engine survival.
Volkswagen mandates oil meeting the VW 502 00 specification, typically a 5W-40 synthetic. Using the correct oil is important for preventing sludge buildup and protecting engine components. Extended drain intervals or incorrect oil will accelerate wear and can lead to premature failure.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with VOLKSWAGEN or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
VOLKSWAGEN Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialVOLKSWAGEN documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed”.
All external links open in new tabs. Please verify current availability of resources.