The Audi CTHG is a 1,968 cc, inline-four turbo-diesel engine produced between 2015 and 2018. It belongs to the Volkswagen Group’s EA288 engine family, designed specifically for Euro 6 compliance. Featuring common rail direct injection, variable geometry turbocharging (VGT), and dual overhead camshafts, it delivers 110 kW (150 PS) and 340 Nm of torque, providing strong low-end pull and refined performance across compact and mid-size Audi models.
Fitted to the 8V A3, 8W A4, and 8S Q3, the CTHG was engineered for drivers seeking efficient, everyday usability with responsive torque delivery. Emissions control is achieved via a multi-stage system: exhaust gas recirculation (EGR) with dual-loop routing, a diesel particulate filter (DPF), and selective catalytic reduction (SCR) using AdBlue injection, allowing full compliance with Euro 6 standards across its production run.
One documented concern is EGR cooler leakage, which can result in coolant contamination of the intake system. This issue, referenced in Audi Service Information Bulletin 2016-10-01, is attributed to thermal stress cracking in the plastic end tanks. From 2017, revised EGR coolers with reinforced polymer construction were introduced to mitigate premature failure.
All CTHG engines meet Euro 6a standards (VCA UK Type Approval #VCA/EMS/7421). No Euro 6d-TEMP variants exist for this engine code.
The Audi CTHG is a 1,968 cc inline-four turbo-diesel engineered for compact and mid-size models (2015–2018). It combines common rail injection with variable geometry turbocharging and SCR-based aftertreatment to deliver strong low-RPM torque. Designed to meet Euro 6a standards, it balances real-world drivability with strict emissions compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,968 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged with variable geometry turbo (VGT) | |
| Bore × stroke | 81.0 mm × 95.5 mm | |
| Power output | 110 kW (150 PS) @ 3,250–4,200 rpm | |
| Torque | 340 Nm @ 1,750–3,000 rpm | |
| Fuel system | Bosch CRS 2-20 common rail (up to 2,000 bar) | |
| Emissions standard | Euro 6a | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled with electric coolant pump | |
| Turbocharger | Single variable-geometry turbo (BorgWarner) | |
| Timing system | Chain-driven (rear-mounted; low wear risk) | |
| Oil type | Audi Longlife Diesel 504.00 / 507.00 (SAE 5W-30) | |
| Dry weight | 148 kg |
The EA288 architecture provides strong low-RPM torque ideal for urban and motorway driving but requires adherence to 15,000 km oil change intervals using Audi-approved Longlife Diesel 504.00/507.00 oil to maintain EGR and turbo longevity. AdBlue consumption must be monitored—average refill every 12,000 km—to prevent SCR system derates. The EGR system is prone to carbon buildup, especially in short-trip use, necessitating periodic cleaning. Coolant contamination from failed EGR coolers (Audi SIB 2016-10-01) can lead to intake manifold clogging and DPF regeneration issues. Post-2017 models benefit from revised EGR cooler design with improved thermal resistance. Emissions systems require regular DTC checks to maintain OBD-II compliance.
Oil Specs: Requires Audi Longlife Diesel 504.00 / 507.00 (5W-30) specification (Audi SIB 2016-10-01). Supersedes ACEA C3 requirements.
Emissions: All CTHG units meet Euro 6a standards (VCA Type Approval #VCA/EMS/7421). No Euro 6d-TEMP certification exists for this engine code.
Power Ratings: Measured under ECE R85 standards. 110 kW output requires EN 590 diesel fuel (Audi TIS Doc. A32605).
Audi Technical Information System (TIS): Docs A32180, A32545, SIB 2016-10-01
VCA Type Approval Database (VCA/EMS/7421)
ISO 8178-4:2022 - Exhaust emissions measurement for reciprocating internal combustion engines
The Audi CTHG was used across Audi's MQB platform with transverse mounting and shared within the Volkswagen Group for longitudinal applications in select models. This engine received platform-specific adaptations-shorter intake tracts in the A3 and revised cooling routing in the Q3-and from 2017 the facelifted A4 B9 adopted the updated EA288evo variant with enhanced EGR cooling, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right side of the cylinder block near the oil filter housing (Audi TIS A32255). The 8th VIN digit indicates engine family ('C' for EA288 series). Pre-2017 units have a black plastic EGR cooler with ribbed end tanks; post-2017 models feature a revised cooler with reinforced polymer construction and updated mounting. Critical differentiation from EA288evo: CTHG lacks the cylinder deactivation system and uses a simpler SCR dosing strategy. Service parts require production date verification—EGR coolers for engines before 06/2017 are incompatible with later units due to redesign (Audi SIB 2016-10-01).
The CTHG's primary reliability risk is EGR cooler failure on early builds, with elevated incidence in mixed driving cycles. Internal Audi quality reports from 2017 indicated a significant share of pre-2017 engines requiring EGR cooler replacement before 120,000 km, while UK DVSA records show increased DPF-related failures linked to coolant contamination in poorly maintained units. Short-trip cycles and extended idling increase thermal stress on the EGR system, making coolant quality and interval adherence critical.
Analysis derived from Audi technical bulletins (2015-2018) and UK DVSA failure statistics (2018-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI CTHG.
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