The Audi CTBA is a 1,968 cc, inline-four turbo-diesel engine produced between 2008 and 2013. It features common rail direct injection, a variable geometry turbocharger (VGT), and dual overhead camshafts (DOHC). In standard output configurations, it delivers 103 kW (140 PS) and 320 Nm of torque, with higher outputs available in tuned variants.
Fitted to models such as the A3 (8P), A4 (B7/B8), A6 (C6/C7), and Q5 (8W), the CTBA was engineered for balanced performance, fuel economy, and refinement in daily driving. Emissions compliance was achieved via exhaust gas recirculation (EGR) and a diesel particulate filter (DPF), allowing Euro 4 and Euro 5 compliance depending on model year and regional specifications.
One documented reliability concern is high-pressure fuel pump (HPFP) wear, particularly on early-build units. This issue, referenced in Audi Service Bulletin 2011-03-01 (Audi SIB 2011-03-01), is linked to fuel quality sensitivity and inadequate lubrication under low-sulfur conditions. From 2011, revised pump internals and updated fuel system calibration were implemented to improve durability.
Production years 2008–2010 meet Euro 4 standards; 2011–2013 models comply with Euro 5 depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Audi CTBA is a 1,968 cc inline-four turbo-diesel engineered for compact and mid-size models (2008–2013). 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 4 and Euro 5 emissions standards, it balances performance with economy across Audi's diesel lineup.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,968 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 81.0 mm × 95.5 mm | |
| Power output | 103–125 kW (140–170 PS) | |
| Torque | 320–350 Nm @ 1,500–2,500 rpm | |
| Fuel system | Bosch CRS 2-20 common-rail (up to 1,600 bar) | |
| Emissions standard | Euro 4 (pre-2011); Euro 5 (2011–2013) | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Garrett GT1749V) | |
| Timing system | Chain-driven (front-mounted, low wear risk) | |
| Oil type | Audi Longlife 03 (SAE 5W-30) | |
| Dry weight | 148 kg |
The CTBA provides strong low-RPM torque ideal for urban and highway driving, but requires adherence to 15,000 km oil change intervals using Audi Longlife 03 (5W-30) to maintain fuel pump and turbo longevity. The Bosch HPFP is sensitive to fuel quality, necessitating ultra-low-sulfur diesel (ULSD) meeting EN 590 standards to prevent premature wear. EGR and DPF systems require regular regeneration and periodic cleaning to avoid flow restrictions and limp mode. Early CTBA units (pre-2011) should be inspected for HPFP wear; updated pumps and calibration revisions post-2011 improved reliability. Cold-start idling should be minimized to reduce EGR soot accumulation.
Oil Specs: Requires Audi Longlife 03 (5W-30) specification (Audi SIB 2011-03-01). Supersedes ACEA B4 and meets VW 505.00 requirements.
Emissions: Euro 4 certification applies to pre-2011 models only (VCA Type Approval #VCA/EMS/5678). Euro 5 compliance confirmed for 2011–2013 builds in EU markets.
Power Ratings: Measured under SAE J1349 standards. 125 kW output requires EU3+ fuel quality and revised ECU calibration (Audi TIS Doc. A20150).
Audi Technical Information System (TIS): Docs A18750, A19230, A20150, SIB 2011-03-01
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The Audi CTBA was used across Audi's 8P/B7/B8/C6/C7 platforms with longitudinal mounting. This engine received platform-specific adaptations-shorter intake manifolds in the A3 and revised cooling routing in the Q5-and from 2011 the facelifted A4 B8.5 adopted updated emissions calibration, 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 timing cover (Audi TIS A18750). The 8th VIN digit indicates engine type ('C' for CTBA series). Pre-2011 models have silver valve covers with black plastic intake manifolds; post-2011 units use black valve covers. Critical differentiation from later EA288 engines: CTBA uses Bosch CRS 2-20 fuel system with round fuel rail access port, while EA288 uses CRS 3-20 with flat access. Service parts require production date verification—HPFP units before 09/2010 are incompatible with post-2011 calibrations due to internal revisions (Audi SIB 2011-03-01).
The CTBA's primary reliability risk is high-pressure fuel pump wear on early builds, with elevated incidence in regions with inconsistent fuel quality. Internal Audi quality reports from 2012 noted a significant share of pre-2011 units requiring pump replacement before 150,000 km, while UK DVSA records show EGR/DPF clogging contributes to a notable portion of emissions-related MOT failures in city-driven vehicles. Extended idling and short trips increase soot accumulation, making regular regeneration and maintenance critical.
Analysis derived from Audi technical bulletins (2009–2014) and UK DVSA failure statistics (2014–2022). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI CTBA.
Comprehensive technical documentation and regulatory references
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AUDI 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.
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