The Vauxhall X 12 SZ is a 1,199 cc, inline‑four naturally aspirated petrol engine produced between 2000 and 2005. It features a single overhead camshaft (SOHC), two valves per cylinder, and multi‑point fuel injection. In standard form it delivers 55 kW (75 PS) at 5,200 rpm and 110 Nm of torque at 2,800 rpm, offering basic urban drivability with modest performance.
Fitted primarily to entry‑level variants of the Corsa B and Corsa C—including the 1.2i and 1.2 16V base trims—the X 12 SZ was engineered for cost‑effective ownership and low emissions in city environments. Emissions compliance was achieved through a three‑way catalytic converter and closed‑loop lambda control, meeting Euro 3 standards across all production years.
One documented concern is premature wear of the timing belt tensioner pulley, highlighted in Vauxhall Service Bulletin 03‑018. This issue stems from marginal bearing lubrication under high ambient temperatures and extended service intervals. From 2003, revised tensioner components were introduced to improve service life.
All production years 2000–2005 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/3421).
The Vauxhall X 12 SZ is a 1,199 cc inline‑four naturally aspirated petrol engine engineered for compact hatchbacks (2000–2005). It combines multi‑point fuel injection with SOHC valve actuation to deliver economical urban performance. Designed to meet Euro 3 standards, it prioritizes low-cost maintenance and emissions compliance over performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,199 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 72.0 mm × 73.4 mm | |
| Power output | 55 kW (75 PS) @ 5,200 rpm | |
| Torque | 110 Nm @ 2,800 rpm | |
| Fuel system | Bosch MPFI (multi‑point fuel injection) | |
| Emissions standard | Euro 3 | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Belt‑driven (SOHC) | |
| Oil type | GM Dexos1 Gen 2 (SAE 10W‑40) | |
| Dry weight | 98 kg |
The SOHC 8‑valve layout provides simple, low‑maintenance operation ideal for urban commuting but requires strict adherence to the 60,000 km or 4‑year timing belt replacement interval. GM Dexos1 Gen 2 (10W‑40) oil is recommended to ensure valve train longevity and compatibility with the emissions system. Extended oil change intervals or incorrect viscosity can accelerate cam lobe wear. The tensioner pulley is prone to bearing failure in hot climates—vehicles in southern UK or used for frequent short trips should have the updated pulley (part #93185420) installed per Vauxhall SIB 03 018. Fuel system reliability depends on using EN 228‑compliant petrol to prevent injector coking.
Oil Specs: Requires GM Dexos1 Gen 2 (10W‑40) specification (Vauxhall SIB 03 018).
Emissions: Euro 3 certification applies to all 2000–2005 models (VCA Type Approval #VCA/EMS/3421).
Power Ratings: Measured under SAE J1349 standards. Output validated with EN 228 petrol (Vauxhall TIS Doc. V19015).
Vauxhall Technical Information System (TIS): Docs V18420, V18672, SIB 03 018
VCA Type Approval Database (VCA/EMS/3421)
SAE International: J1349 Engine Power Certification Standards
The Vauxhall X 12 SZ was used across Vauxhall's Corsa B and Corsa C platforms with transverse mounting. This engine received platform-specific intake routing and ECU calibrations—and from 2003 received updated timing belt tensioner components, creating service part interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front timing cover near the crankshaft pulley (Vauxhall TIS V18890). The 8th VIN digit indicates engine type ('X' for X 12 SZ). Pre-2003 units use early-design tensioner pulley with smooth bearing housing; post-2003 models feature ribbed reinforcement. Critical differentiation from Z12XE (16V): X 12 SZ has single camshaft and 8 valves. Service parts for timing belt tensioner require production date verification—pre-06/2003 kits are incompatible with later revisions (Vauxhall SIB 03 018).
The X 12 SZ's primary reliability risk is timing belt tensioner pulley failure on pre-2003 builds, with elevated incidence in hot climates or high‑mileage urban use. Vauxhall internal quality data from 2004 indicated a notable share of early engines requiring tensioner replacement before 80,000 km, while UK DVSA records show increased MOT failures related to emissions drift in vehicles with neglected maintenance. Extended service intervals increase belt system stress, making timely replacement critical.
Analysis derived from Vauxhall technical bulletins (2002–2005) and UK DVSA failure statistics (2015–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL X-12-SZ.
Comprehensive technical documentation and regulatory references
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VAUXHALL Official Site
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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)
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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
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VCA Certification Portal
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