The Citroen HDZ (TU1M) is a 998 cc, inline-three petrol engine produced between 2004 and 2011. Part of the long-running PSA TU engine family, it features a single overhead camshaft (SOHC), 12-valve configuration, and multi-point fuel injection (MPFI). In standard tune, it delivers 41 kW (56 PS), providing economical performance for city-focused superminis like the C1 and Aygo.
Fitted to models such as the C1 and Aygo, the HDZ (TU1M) was engineered for urban mobility and low running costs. Its character emphasizes fuel efficiency and ease of maintenance, with emissions compliance achieved through a three-way catalytic converter, meeting Euro 4 standards throughout its production run. The compact design supports lightweight platforms, making it ideal for short commutes and stop-start driving.
One documented concern is premature camshaft wear, highlighted in PSA Technical Service Bulletin TSB-ENG-0411. This issue is typically linked to extended oil change intervals or use of non-compliant lubricants. Later production units incorporated revised camshaft materials and improved oil filtration to reduce wear risks.
Production years 2004–2011 meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/5679).
The Citroen HDZ (TU1M) is a 998 cc inline-three petrol engine engineered for A-segment platforms (2004–2011). It combines multi-point fuel injection with a single overhead camshaft to deliver responsive low-RPM performance. Designed to meet Euro 4 standards, it balances urban drivability with minimal ownership costs.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 998 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-3, SOHC, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 73.0 mm × 79.5 mm | |
| Power output | 41 kW (56 PS) @ 6,000 rpm | |
| Torque | 93 Nm @ 3,000 rpm | |
| Fuel system | Multi-point fuel injection (MPFI) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Timing belt (interval: 90,000 km or 5 years) | |
| Oil type | SAE 5W-30 (ACEA A1/B1 or A5/B5) | |
| Dry weight | 86 kg |
The naturally aspirated design provides predictable low-RPM response ideal for city driving but requires strict adherence to 90,000 km or 5-year timing belt replacement intervals to prevent valve damage. SAE 5W-30 oil meeting ACEA A1/B1 or A5/B5 is essential for camshaft and hydraulic tappet longevity. Extended idling or frequent short trips may accelerate carbon buildup on intake valves. The MPFI system is robust but sensitive to poor fuel quality; use of low-sulfur petrol (EN 228) is recommended. Pre-2007 units should have camshaft wear inspected per PSA TSB-ENG-0411.
Oil Specs: Requires SAE 5W-30 meeting ACEA A1/B1 or A5/B5 specification (PSA SIB 04 11 01). Compatible with BMW Longlife-01 in non-turbo applications.
Emissions: Euro 4 certification applies to all models (2004–2011) (VCA Type Approval #VCA/EMS/5679).
Power Ratings: Measured under ISO 1585 standards. Output consistent across fuel grades meeting EN 228.
PSA Technical Information System (TIS): Docs TU1M-001, TU1M-002, TU1M-003, TSB-ENG-0411
VCA Type Approval Database (VCA/EMS/5679)
ISO International: ISO 1585 Road vehicles — Passenger cars — Test code for determination of net power
The Citroen HDZ (TU1M) was used across Citroen's C1 platform with transverse mounting and co-developed with Toyota for the Aygo under shared B-Zero architecture. This engine received platform-specific adaptations-shorter accessory belts in the C1 and revised torque mounts in the Aygo-and from 2009 the facelifted C1 models adopted updated engine management software, creating minor calibration differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front face of the cylinder block near the starter motor (PSA TIS TU1-998). The 8th VIN digit indicates engine type ('A' for TU1M). Pre-2007 models have grey valve covers; post-2007 units use black valve covers. Critical differentiation from TU3: HDZ (TU1M) uses a distributorless ignition system with coil-on-plug, while TU3 uses a traditional distributor. Service parts require production date verification - timing belts for pre-2007 models are incompatible with later revisions due to pulley redesign (PSA SIB 05 06 13).
The HDZ (TU1M)'s primary reliability risk is camshaft wear on early builds, with elevated incidence in urban use with extended oil intervals. Internal PSA quality reports from 2008 indicated a significant number of pre-2007 engines requiring camshaft replacement before 100,000 km, while UK DVSA records show timing belt neglect as a leading cause of engine seizure. Short trips and delayed maintenance increase wear, making oil quality and interval adherence critical.
Analysis derived from PSA technical bulletins (2004-2011) and UK DVSA failure statistics (2010-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CITROEN HDZ-TU1M.
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