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 K12B was engineered for compact city car efficiency and low emissions. Emissions compliance was achieved through precise electronic throttle control, Dualjet injection, and a three‑way catalytic converter, allowing adherence to Euro 5 standards across its production run.
One documented concern is premature wear of the hydraulic tappets, highlighted in Vauxhall Service Bulletin 10‑018. This issue is linked to oil viscosity degradation and infrequent oil changes, leading to noisy valve trains and potential cam lobe wear. From mid‑2012, revised tappet materials and updated oil pump specifications were introduced to improve durability.
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 Dualjet system enhances fuel atomization for improved combustion efficiency, ideal for stop-start urban driving. However, the hydraulic tappet design demands strict adherence to 15,000 km oil change intervals using ACEA A3/B4 5W‑30 oil to prevent noise and wear. Degraded oil viscosity accelerates tappet wear, potentially damaging cam lobes. Post‑2012 engines include updated tappet materials per Vauxhall SIB 10 018. The non‑interference chain design eliminates catastrophic failure risk, but oil quality remains critical for valvetrain longevity.
Oil Specs: Requires ACEA A3/B4 (5W-30) specification (Vauxhall SIB 10 018).
Emissions: Euro 5 certification applies to all 2009–2015 models (VCA Type Approval #VCA/EMS/5432).
Power Ratings: Measured under SAE J1349 standards. Output validated on EU95 petrol (Vauxhall TIS Doc. V12210).
Vauxhall Technical Information System (TIS): Docs V12110, V12115, SIB 10 018
Suzuki Parts Catalogue (EPC) K12B-01
VCA Type Approval Database (VCA/EMS/5432)
SAE International: J1349 Engine Power Certification Standards
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.
Locate the engine code stamped on the front timing cover near the crankshaft pulley (Vauxhall TIS V12180). The 7th VIN digit indicates engine family ('K' for K12 series). All K12B units feature a black aluminium valve cover with “K12B” embossed. Critical differentiation from Vauxhall’s own A12XER: K12B has Suzuki-style coil-on-plug ignition, a single serpentine belt, and Dualjet injectors with twin nozzles per cylinder. Service parts for hydraulic tappets differ before and after production date 07/2012 (Vauxhall SIB 10 018).
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.
Find answers to most commonly asked questions about VAUXHALL K12B.
Comprehensive technical documentation and regulatory references
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GOV.UK: Vehicle Approval & V5C
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DVLA: Engine Changes & MoT
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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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