The Vauxhall A20DTJ is a 1,956 cc, inline‑four turbo‑charged diesel engine produced between 2017 and 2022. It features a DOHC 16‑valve layout with high-pressure common‑rail direct injection and a twin‑scroll variable geometry turbocharger. In standard form it delivered 100 kW (136 PS) and 320 Nm of torque, optimized for responsive low‑end pull and refined cruising.
Fitted primarily to the Astra K and Insignia B, the A20DTJ was engineered for compliance with Euro 6d‑TEMP emissions standards. This was achieved through a combination of cooled exhaust gas recirculation (EGR), a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) system using AdBlue®.
One documented concern is premature failure of the high-pressure fuel pump (HPFP) drive mechanism, which can cause hard starting or rail pressure faults. This issue, referenced in Vauxhall Service Bulletin TIS 18‑045, is linked to insufficient lubrication under extended oil change intervals or use of non‑Dexos2‑approved lubricants. Later production units incorporated revised pump internals and camshaft drive profiles to improve reliability.
Production years 2017–2022 meet Euro 6d-TEMP standards (VCA UK Type Approval #VCA/EMS/9421).
The Vauxhall A20DTJ is a 1,956 cc inline‑four turbo‑diesel engineered for compact and mid‑size models (2017–2022). It combines Bosch common‑rail injection with a twin‑scroll VGT turbocharger to deliver strong low‑rpm torque and smooth power delivery. Designed to meet Euro 6d-TEMP emissions standards, it integrates AdBlue® SCR technology alongside EGR and DPF systems for regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,956 cc | |
| Fuel type | Diesel (EN 590) | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 83.0 mm × 90.4 mm | |
| Power output | 100 kW (136 PS) @ 3,750 rpm | |
| Torque | 320 Nm @ 1,500–2,250 rpm | |
| Fuel system | Bosch CP4.2 common‑rail (up to 2,000 bar) | |
| Emissions standard | Euro 6d-TEMP | |
| Compression ratio | 15.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Twin‑scroll variable‑geometry turbo (Garrett VNT20) | |
| Timing system | Chain (front‑mounted) | |
| Oil type | GM Dexos2 (SAE 5W‑30) | |
| Dry weight | 148 kg |
The twin-scroll VGT turbo and SCR/AdBlue system provide strong low-end torque and emissions compliance but require strict adherence to 15,000 km oil change intervals using GM Dexos2 (5W‑30) to prevent HPFP drive wear and turbo degradation. Ultra-low-sulfur diesel (EN 590) is essential to avoid high-pressure pump seizure. Frequent short trips may lead to AdBlue crystallization or incomplete DPF regeneration. Vauxhall SIB 18‑045 recommends HPFP inspection if hard-start symptoms occur before 120,000 km, especially in vehicles with non‑compliant oil history.
Oil Specs: Requires GM Dexos2 (5W‑30) specification (Vauxhall SIB 18‑045). Not interchangeable with older GM-LL-A-025.
Emissions: Euro 6d-TEMP certification applies to all 2017–2022 A20DTJ models (VCA Type Approval #VCA/EMS/9421).
Power Ratings: Measured under SAE J1349 standards. Peak output assumes EN 590 diesel quality (Vauxhall TIS Doc. A20‑6701).
Vauxhall Technical Information System (TIS): Docs A20‑6630, A20‑6655, SIB 18‑045
VCA Type Approval Database (VCA/EMS/9421)
SAE International: J1349 Engine Power Certification Standards
The Vauxhall A20DTJ was used across Vauxhall's Astra K and Insignia B platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations—revised AdBlue tank routing in the Insignia and modified engine mounts in the Astra—and from 2020 the facelifted Astra K MY20 models adopted updated ECU calibrations, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front timing cover near the crank pulley (Vauxhall TIS A20‑6635). The 7th VIN digit indicates engine family ('0' for A20 series). All A20DTJ units feature a black plastic cam cover with “2.0 CDTi” badge and an AdBlue dosing unit mounted near the exhaust manifold. Critical differentiation from A20DTH: A20DTJ uses Bosch EDC17C74 ECU with AdBlue/SCR; A20DTH (non-SCR) uses EDC17C10. ECU and injector part numbers must match application—interchange between SCR and non-SCR variants is not supported (Vauxhall SIB 17‑033).
The A20DTJ's primary reliability risk is high-pressure fuel pump (HPFP) drive wear, with elevated incidence in vehicles using non‑Dexos2 oil or extended service intervals. Vauxhall internal data from 2020 indicated a measurable uptick in HPFP-related warranty claims before 120,000 km, while UK DVSA records show minimal emissions failure correlation due to robust SCR monitoring. Oil quality and change discipline make HPFP longevity critical.
Analysis derived from Vauxhall technical bulletins (2017–2021) and UK DVSA failure statistics (2018–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL A-20-DTJ.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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