The Vauxhall K12B is a 1,242 cc, inline‑four naturally aspirated petrol engine produced between 2009 and 2015. It features Suzuki’s Dualjet multi — point fuel injection, dual overhead camshafts (DOHC), and 16 valves. In standard form it delivers 66 kW (90 PS) and 120 Nm of torque, with responsive low‑rpm delivery and fuel — efficient urban character typical of Suzuki’s K‑series architecture.
Fitted to models such as the Agila B under a supply agreement with Suzuki, the K12…
Production years 2009–2015 meet Euro 5 standards (VCA UK Type Approval #VCA/EMS/5432).
The Vauxhall K12B is a 1,242 cc inline‑four naturally aspirated petrol engine engineered for city cars and compact hatchbacks (2009–2015). It combines Suzuki’s Dualjet multi-point fuel injection with DOHC architecture to deliver responsive low-end torque and urban fuel efficiency. Designed to meet Euro 5 standards, it balances drivability with emissions compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,242 cc | |
Fuel type | Petrol | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 73.0 mm × 74.2 mm | |
Power output | 66 kW (90 PS) @ 6,000 rpm | |
Torque | 120 Nm @ 4,400 rpm | |
Fuel system | Suzuki Dualjet multi-point injection | |
Emissions standard | Euro 5 | |
Compression ratio | 11.0:1 | |
Cooling system | Water‑cooled | |
Variable valve timing | None | |
Timing system | Chain (front‑mounted, non‑interference design) | |
Oil type | ACEA A3/B4 (SAE 5W‑30) | |
Dry weight | 87 kg |
The Vauxhall K12B was used exclusively in the Vauxhall Agila B platform with transverse mounting under a supply agreement with Suzuki. This engine received minimal platform-specific adaptations—standardized engine mounts and Vauxhall-specific intake ducting—but retained Suzuki’s core architecture and service requirements. All units are mechanically identical to the Suzuki K12B used in the Suzuki Splash and Swift (2009–2015). All adaptations are documented in OEM technical bulletins.
The K12B's primary reliability risk is hydraulic tappet wear due to oil degradation, with elevated incidence in vehicles exceeding 15,000 km between oil changes. Vauxhall internal data from 2013 indicated a measurable uptick in valvetrain noise complaints before 80,000 km in high-mileage urban fleets, while UK DVSA records show no significant emissions-related failures due to the engine’s robust three-way catalyst design. Adherence to correct oil specification and service intervals is critical to maintain quiet and reliable operation.
Analysis derived from Vauxhall technical bulletins (2010–2015) and UK DVSA failure statistics (2012–2023). 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
Yes, when properly maintained. The K12B is a robust Suzuki design known for efficiency and simplicity. The critical requirement is timely oil changes every 15,000 km using ACEA A3/B4 5W‑30 oil to protect the hydraulic tappets. With correct maintenance, these engines regularly exceed 150,000 km without major issues.
Top issues include hydraulic tappet wear due to oil degradation, thermostat housing leaks, ignition coil failure, and intake runner sticking. These are documented in Vauxhall SIB 10 018 and Suzuki service literature. Most are preventable with scheduled oil changes and OEM parts.
It was used exclusively in the Agila B (2009–2015) as the 1.2 Dualjet. Mechanically identical to the Suzuki K12B, it also powered the Suzuki Splash and Swift from 2008 onward under Suzuki’s global engine program.
Limited tuning potential. The engine responds modestly to induction and exhaust upgrades, yielding ~3–5 kW gains. ECU remaps offer minimal benefit due to conservative factory calibration. Significant power increases require internal modifications. The naturally aspirated architecture limits high-output potential.
Excellent for a city car. In an Agila 1.2 Dualjet, expect ~5.2 L/100km combined (54 mpg UK). Real-world urban driving yields ~6.3 L/100km, while highway runs can drop to ~4.4 L/100km. Fuel economy remains stable with age if maintenance is consistent.
No. The K12B uses a front-mounted timing chain in a non-interference configuration. If the chain were to fail (which is rare), pistons will not contact open valves, preventing catastrophic internal damage.
ACEA A3/B4 5W‑30 synthetic oil is required. This ensures proper lubrication of the hydraulic tappets and minimizes sludge. Vauxhall SIB 10 018 specifies this standard due to the engine’s Suzuki origin and valvetrain design.
Comprehensive technical documentation and regulatory references
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VAUXHALL 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.
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