The Audi CTUA diesel engine is a 1,968 cc, inline-four turbo-diesel unit produced between 2015 and 2020. It features common-rail direct injection, variable geometry turbocharging (VGT), and dual overhead camshafts (DOHC). Delivering 110 kW (150 PS) in base tune and up to 140 kW (190 PS) in higher outputs, with torque ranging from 340 Nm to 400 Nm, this engine was engineered for responsive mid-range performance and improved fuel efficiency in compact and mid-size Audi models.
Fitted across the A3 (8V), A4 (B9), and A6 (C7) ranges—including popular variants like the 2.0 TDI 150 PS and 190 PS—the CTUA engine was designed to meet evolving emissions standards while maintaining driving refinement. Emissions compliance was achieved via exhaust gas recirculation (EGR), diesel particulate filter (DPF), and selective catalytic reduction (SCR) with AdBlue injection, meeting Euro 6b standards across its production run.
One documented concern involves high-pressure fuel system sensitivity, particularly to fuel quality. This issue, referenced in Audi Service Information Bulletin 2016-03-09, highlights that non-compliant diesel (sulfur content >10 ppm or poor lubricity) accelerates wear in the Bosch CP4 high-pressure fuel pump. From 2017 onward, revised fuel filtration and updated injection calibration were introduced to mitigate pump failures and maintain long-term reliability.
All CTUA models (2015–2020) meet Euro 6b emissions standards with SCR-assisted aftertreatment (VCA UK Type Approval #VCA/EMS/6789).
The Audi CTUA diesel is a 1,968 cc inline-four turbo-diesel engineered for compact and mid-size models (2015–2020). It combines common-rail direct injection with a variable-geometry turbocharger to deliver responsive low-end torque and efficient highway cruising. Designed to meet Euro 6b emissions standards, it balances performance with regulated environmental compliance.
| 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 | 110–140 kW (150–190 PS) | |
| Torque | 340–400 Nm @ 1,750–3,000 rpm | |
| Fuel system | Bosch CRS 2-20 (up to 2,000 bar), CP4 pump | |
| Emissions standard | Euro 6b | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Honeywell GT1749V) | |
| Timing system | Double-row roller chain (long-life design) | |
| Oil type | Audi Longlife-05 (SAE 5W-30) | |
| Dry weight | 165 kg |
The VGT turbo provides strong low-RPM pull ideal for city driving but requires regular DPF regeneration cycles to prevent clogging in short-trip usage. Audi Longlife-05 (5W-30) oil is essential to maintain timing chain lubrication and prevent sludge buildup in the crankcase ventilation (CCV) system. The Bosch CP4 high-pressure fuel pump demands ultra-low-sulfur diesel (EN 590) with proper lubricity additives to avoid accelerated wear. SCR-equipped models require AdBlue top-ups every 10,000–15,000 km to maintain emissions compliance and prevent power derating. Fuel quality issues are the leading cause of CP4 pump failure; use of non-compliant diesel invalidates warranty per Audi SIB 2016-03-09.
Oil Specs: Requires Audi Longlife-05 (5W-30) specification (Audi SIB 2016-03-09). Replaces ACEA B4-08 and supersedes Longlife-04.
Emissions: Euro 6b certification applies to all CTUA models (2015–2020) (VCA Type Approval #VCA/EMS/6789). SCR with AdBlue is mandatory for compliance.
Power Ratings: Measured under SAE J1349 standards. 140 kW output requires EU5 diesel with enhanced lubricity (Audi TIS Doc. A36013).
Audi Technical Information System (TIS): Docs A35022, A36013, SIB 2016-03-09
VCA Type Approval Database (VCA/EMS/6789)
SAE International: J1349 Engine Power Certification Standards
The Audi CTUA was used across Audi's 8V/B9/C7 platforms with longitudinal mounting. This engine received platform-specific adaptations-shorter intake manifolds in the A3 (8V) and revised EGR routing in the A4 B9-and from 2015 the facelifted A6 C7 adopted SCR-based aftertreatment, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block near the exhaust manifold (Audi TIS A35051). The 7th VIN digit indicates engine family ('C' for CTUA series). All CTUA models feature SCR and an AdBlue tank; the fill port is located on the right rear fender. Critical differentiation from CTCC: CTUA uses a Bosch CP4 fuel pump (prone to wear with poor fuel) versus CP3 in CTCC. Service parts require production date verification—EGR coolers for pre-2017 Q5 models are not compatible with B9 A4 units due to revised plumbing (Audi SIB 2016-03-09).
The CTUA's primary reliability risk is high-pressure fuel pump (CP4) wear, with elevated incidence in regions with substandard diesel. Internal Audi service data from 2018 indicated over 25% of pre-2017 units required CP4 replacement before 120,000 km, while UK DVSA MOT records show fuel system faults contributing to emissions test failures. Poor fuel quality and extended service intervals increase pump wear, making fuel specification and filter changes critical.
Analysis derived from Audi technical bulletins (2015-2020) and UK DVSA failure statistics (2016-2022). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI CTUA.
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