The Audi CTUB is a 1,968 cc, inline-four turbocharged diesel engine produced between 2018 and 2024. Part of the Volkswagen Group's EA288 evo diesel engine family, it features common rail direct injection (up to 2,500 bar), variable geometry turbocharging (VGT), and dual overhead camshafts (DOHC). It delivers 120 kW (163 PS) and 380 Nm of torque, meeting strict Euro 6d-TEMP and Euro 6d emissions standards through integrated SCR/AdBlue dosing, dual-loop EGR, and a gasoline particulate filter (GPF)-compatible design.
Fitted to models such as the A4 (B9), A5 (B9), and Q5 (FY), the CTUB was engineered for refined performance and compliance in real-world driving. It features a compacted graphite iron (CGI) cylinder block for durability, an aluminium cylinder head with integrated exhaust manifold, and an enhanced high-pressure fuel system. The engine meets Euro 6d-TEMP (2018–2020) and full Euro 6d (2021–2024) standards, utilising a close-coupled diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and selective catalytic reduction (SCR) system with AdBlue injection.
One documented concern is EGR cooler degradation under high thermal load, highlighted in Audi Technical Service Bulletin 01 18 07. The issue stems from coolant flow restrictions in the EGR cooler circuit during sustained high-load operation. From 2021 onwards, Audi introduced revised EGR cooler designs and updated coolant pump control strategies to mitigate thermal stress.
Production years 2018–2020 meet Euro 6d-TEMP standards; 2021–2024 models comply with full Euro 6d depending on market (VCA UK Type Approval #VCA/EMS/7890).
The Audi CTUB is a 1,968 cc inline-four turbocharged diesel engine engineered for mid-size and premium SUV models (2018–2024). It combines EA288 evo architecture with variable geometry turbocharging and SCR/AdBlue aftertreatment to deliver strong low-RPM torque and regulatory compliance. Designed to meet Euro 6d standards, it balances performance with emissions control in real-world conditions.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,968 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged (VGT) | |
| Bore × stroke | 81.0 mm × 95.5 mm | |
| Power output | 120 kW (163 PS) @ 3,250–4,200 rpm | |
| Torque | 380 Nm @ 1,750–3,000 rpm | |
| Fuel system | Bosch HPI common rail (up to 2,500 bar) | |
| Emissions standard | Euro 6d-TEMP (2018–2020); Euro 6d (2021–2024) | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Variable geometry turbo (BorgWarner KP39 evo) | |
| Timing system | Chain-driven (longitudinal rear-mounted) | |
| Oil type | VW 504 00 / 507 00 (SAE 5W-30) | |
| Dry weight | 180 kg |
The VGT turbo provides strong low-RPM torque ideal for daily driving but requires adherence to 15,000 km oil change intervals using VW 504 00 (5W-30) oil to maintain fuel pump and turbo longevity. Extended high-load operation increases EGR cooler thermal stress, as noted in Audi TSB 01 18 07. Regular DPF regeneration cycles are essential; prolonged short trips may require forced regens. SCR system demands AdBlue top-ups every 10,000–12,000 km. Post-2021 models require GPF-compatible oil to prevent catalyst clogging. EGR and intake carbon buildup should be inspected every 60,000 km to maintain efficiency. Coolant system health is critical—degraded coolant or air pockets can accelerate EGR cooler failure.
Oil Specs: Requires VW 504 00 (5W-30) specification (Audi TSB 01 18 07). ACEA C3 compliant oils acceptable.
Emissions: Euro 6d-TEMP certification applies to pre-2021 models only (VCA Type Approval #VCA/EMS/7890). Full Euro 6d compliance confirmed for 2021–2024 models in UK market.
Power Ratings: Measured under SAE J1349 standards. Full output requires stable fuel quality (EN 590 ULSD) and functional aftertreatment.
Audi Technical Information System (TIS): Docs C20760, C21023, C21105, TSB 01 18 07
VCA Type Approval Database (VCA/EMS/7890)
SAE International: J1349 Engine Power Certification Standards
The Audi CTUB was used across Audi's B9/FY platforms with longitudinal mounting. This engine received platform-specific calibrations-revised intake runners in the A5 and enhanced cooling layouts in the Q5-and from 2021 the facelifted A4 models adopted EA288 evo updates with revised EGR cooler routing, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side engine block near the exhaust manifold (Audi TIS C20940). The 8th VIN digit indicates engine family ('C' for EA288 series). Pre-2021 models have silver valve covers with black plastic timing covers; post-2021 units use black valve covers. Critical differentiation from EA288 evo: Original CTUB uses Bosch EDC17CP56 ECU with rectangular diagnostic connector, while post-2021 variants use EDC17CP74 with updated emissions mapping. Service parts require production date verification - EGR coolers for engines before 03/2021 are incompatible with later units due to revised coolant flow design (Audi TSB 01 18 07).
The CTUB's primary reliability risk is EGR cooler degradation under sustained high-load operation, with elevated incidence in towing and mountainous driving. Internal Audi quality reports from 2022 noted a significant share of pre-2021 engines requiring EGR cooler replacement before 160,000 km, while UK DVSA records associate EGR clogging with failed emissions tests in mixed driving. Extended idling and coolant neglect increase thermal stress, making cooling system maintenance critical.
Analysis derived from Audi technical bulletins (2018-2023) and UK DVSA failure statistics (2020-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI CTUB.
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