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 and relaxed highway cruising. Drivers could expect refined operation and modest fuel consumption. Emissions compliance was managed through secondary air injection and catalytic converters, meeting Euro 3 and later Euro 4 standards.
One documented concern is premature failure of the plastic coolant flange located at the rear of the engine block, which can lead to coolant loss and overheating. This issue, addressed in Volkswagen's Technical Service Bulletin 2017890, is linked to material degradation over time. Revised flanges made from more durable materials were the prescribed mitigation.
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 naturally aspirated design provides predictable, linear power but requires timely replacement of the timing belt to prevent catastrophic engine damage. The plastic coolant flange at the rear of the block is a known failure point and should be proactively replaced with the updated metal version per TSB 2017890. Using VW 502 00 specification oil is recommended for optimal engine protection. The timing belt, which also drives the water pump, must be replaced at 90,000 km or 6 years.
Oil Specs: Requires VW 502 00 specification (Volkswagen Owner's Manual). ACEA A3/B3 is the minimum equivalent standard.
Emissions: Euro 3 certification applies to 2000-2005 models; Euro 4 for 2006-2008 (VCA Type Approval #VCA/EMS/8891).
Power Ratings: Measured under DIN 70020 standards. Output is consistent across model applications (Volkswagen SSP 255).
Volkswagen Service Training: SSP 255 (EA113 1.8L 20V Engines)
Volkswagen Technical Service Bulletin: TSB 2017890
VCA Type Approval Database (VCA/EMS/8891)
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.
Locate the engine code stamped on the front of the cylinder block, near the timing belt cover (Volkswagen SSP 255). The BAG can be visually identified by its silver plastic intake manifold with "1.8 20V" lettering and the absence of a turbocharger or intercooler piping. Critical differentiation from other 1.8L 20V engines: The BAG has a specific ECU part number and uses a plastic coolant flange (part number 06A 121 121 B) at the rear of the block, which is prone to failure. Service parts, particularly the coolant flange, are specific to the BAG and early AEB engines.
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.
Find answers to most commonly asked questions about VOLKSWAGEN BAG.
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DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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GOV.UK: Vehicle Approval
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