The Vauxhall A20 DTH is a 1,956 cc, inline‑four turbo‑diesel engine produced between 2006 and 2011. It features a double overhead camshaft (DOHC), 16‑valve configuration with common‑rail direct fuel injection, delivering 100 kW (136 PS) and 320 Nm of torque. The cast‑iron block and aluminium head balance strength with weight, while variable geometry turbocharging ensures responsive low‑end performance.
Fitted to models such as the Vectra C, Signum, and Zafira B—including the 2.0 CDTi variants—the A20 DTH was engineered for drivers seeking refined diesel performance with strong motorway capability. Emissions compliance was achieved through cooled exhaust gas recirculation (EGR) and a diesel oxidation catalyst, meeting Euro 4 standards throughout its production run.
One documented concern is premature failure of the high‑pressure fuel pump drive coupling, highlighted in Vauxhall Technical Service Bulletin TSB‑07‑33. This is often linked to insufficient lubrication from extended oil change intervals or use of non‑specified oil grades. Later service procedures mandated revised pump drive components and stricter oil specifications.
Production years 2006–2011 meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/8912).
The Vauxhall A20 DTH is a 1,956 cc inline‑four turbo‑diesel engineered for mid‑size sedans, estates, and MPVs (2006–2011). It combines common‑rail direct injection with a variable geometry turbocharger to deliver strong low‑rpm torque and smooth high‑speed cruising. Designed to meet Euro 4 emissions standards, it balances performance with fuel efficiency.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,956 cc | |
| Fuel type | Diesel | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 86.0 mm × 86.0 mm | |
| Power output | 100 kW (136 PS) @ 4,000 rpm | |
| Torque | 320 Nm @ 2,000 rpm | |
| Fuel system | Bosch CP3 common‑rail (up to 1,600 bar) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Variable geometry turbo (Garrett) | |
| Timing system | Chain‑driven camshafts | |
| Oil type | ACEA B4 or API CF (SAE 5W‑30) | |
| Dry weight | 142 kg |
The DOHC common‑rail layout delivers strong torque and refinement but requires strict adherence to 15,000 km oil change intervals with ACEA B4 or API CF 5W‑30 oil to protect the high‑pressure fuel pump drive. Extended intervals or incorrect oil accelerate wear in the CP3 pump coupling, potentially causing hard starts or pump seizure. The chain‑driven timing system is generally durable but should be inspected for guide wear after 200,000 km. Fuel must meet EN 590 ultra‑low‑sulfur diesel (ULSD) standards to prevent injector and pump degradation.
Oil Specs: Requires ACEA B4 or API CF (5W‑30) specification (Vauxhall Owner Manual 2007). Modern ACEA C3 oils are not recommended due to sulfated ash content.
Emissions: Euro 4 certification applies to all 2006–2011 A20 DTH units (VCA Type Approval #VCA/EMS/8912). No Euro 5 variants produced.
Power Ratings: Measured under ISO 1585 standards. Output verified on dynamometer per Vauxhall PT‑2008.
Vauxhall Technical Information System (TIS): Docs V06‑328, V07‑112
Vauxhall Technical Service Bulletins: TSB‑07‑33
VCA Type Approval Database (VCA/EMS/8912)
ISO 1585: Road vehicles — Engine test code
The Vauxhall A20 DTH was used across Vauxhall's Vectra C, Signum, and Zafira B platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations—reinforced engine mounts in the Signum for NVH control and modified exhaust manifolds in the Zafira B—and from 2008 the facelifted Vectra C models adopted updated EGR coolers, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front face of the cylinder block adjacent to the timing cover (Vauxhall TIS V06‑328). The 8th VIN digit indicates engine displacement ('2' for 2.0L). A20 DTH units feature a black aluminium valve cover with “20DT” embossed and a Bosch CP3 high-pressure fuel pump mounted on the right side. Critical differentiation from A20DTR: A20 DTH uses a fixed-output CP3 pump and Euro 4 emissions; A20DTR features a CP4 pump and Euro 5 compliance. ECU part numbers beginning with “20DTH” confirm application.
The A20 DTH's primary reliability risk is high-pressure fuel pump drive coupling wear, with elevated incidence in high-mileage or poorly maintained examples. Vauxhall internal service data from 2009 indicated a notable share of pre-2008 engines requiring pump coupling replacement before 150,000 km, while UK DVSA records show EGR-related advisories as common MOT items. Extended oil intervals and incorrect oil grades make proper maintenance critical.
Analysis derived from Vauxhall technical bulletins (2006–2011) and UK DVSA failure statistics (2010–2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL A-20-DTH.
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