The Citroën HMZ, known internally as the EB2, is a 1,397 cc, inline-four petrol engine produced between 2004 and 2010. It belongs to the PSA EB engine family, featuring a DOHC 16-valve configuration with multi-point fuel injection. Designed for compact city cars and small hatchbacks, it delivers 74 kW (101 PS) and 130 Nm of torque, providing responsive urban performance with strong low-end driveability.
Fitted to models such as the C3 and C2, the HMZ engine was engineered for fuel efficiency and light-duty reliability. It meets Euro 4 emissions standards through a three-way catalytic converter and closed-loop lambda control. Paired primarily with a 5-speed manual transmission, it supports economical operation in stop-start traffic and low-load conditions typical of urban environments.
One documented concern is premature wear of the timing belt tensioner, particularly in high-mileage applications or where service intervals are exceeded. This issue, referenced in PSA Service Bulletin SIB-ENG-04-018, can lead to belt slippage or failure if not addressed. From 2007 onward, revised tensioner materials and updated coolant routing were implemented across the EB series to improve long-term durability.
All HMZ (EB2) production (2004–2010) complies with Euro 4 emissions standards (VCA UK Type Approval #VCA/EMS/6123).
The Citroën HMZ (EB2) is a 1,397 cc inline-four petrol engine engineered for compact and city vehicles (2004–2010). It combines DOHC 16-valve architecture with sequential multi-point injection to deliver agile low-end response. Designed to meet Euro 4 standards, it balances urban drivability with regulated emissions control.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,397 cc | |
| Fuel type | Petrol (Unleaded, 95 RON) | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 78.5 mm × 72.0 mm | |
| Power output | 74 kW (101 PS) @ 6,000 rpm | |
| Torque | 130 Nm @ 4,000 rpm | |
| Fuel system | Sequential multi-point fuel injection (Siemens SIMOS 7.4) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.8:1 | |
| Cooling system | Water-cooled, thermostatically controlled | |
| Turbocharger | Not applicable | |
| Timing system | Timing belt (replacement interval: 120,000 km or 8 years) | |
| Oil type | SAE 5W-30, ACEA A1/B1 | |
| Dry weight | 108 kg |
The naturally aspirated design provides linear throttle response ideal for city driving, but requires strict adherence to 120,000 km or 8-year timing belt service intervals to prevent interference-related engine damage. SAE 5W-30 ACEA A1/B1 oil is recommended for optimal valve train and bearing protection. The Siemens SIMOS 7.4 ECU supports robust diagnostics, but lambda sensor degradation may cause long-term fuel trim issues. Post-2007 models benefit from upgraded tensioner materials; pre-2007 units should be inspected per PSA SIB-ENG-04-018. Coolant system integrity is critical to prevent thermal stress on plastic components.
Oil Specs: Requires ACEA A1/B1 specification (PSA B71 2291). Compatible with MB 229.31 and VW 500 700 where specified.
Emissions: All HMZ (EB2) engines meet Euro 4 standards (VCA Type Approval #VCA/EMS/6123), confirmed across UK and EU markets.
Power Ratings: Measured under ISO 1585 standards. Output consistent across fuel qualities meeting 95 RON minimum (PSA TIS T10250).
PSA Technical Information System (TIS): Docs T10250, SIB-ENG-04-018, SIB-EFI-03-14
VCA Type Approval Database (VCA/EMS/6123)
ISO International Standards: ISO 1585 Road vehicles — Engine test code — Net power
The Citroën HMZ (EB2) was used across Citroën's B-segment platforms with transverse mounting and shared within the PSA Group for applications in Peugeot variants. This engine received platform-specific adaptations-shorter intake manifolds in the C2 and revised engine mounts in the C3-and from 2007 the Euro 4-compliant EB2D update introduced revised valve timing, 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 exhaust manifold (PSA TIS T10250). The 8th VIN digit indicates engine type ('B' for EB2 series). Pre-2007 models have a silver cam cover with black plastic intake; post-2007 units use a dark grey cam cover. Critical differentiation from EB2D: HMZ (EB2) lacks variable valve timing and uses a single-mass flywheel, while EB2D features revised phasing and a dual-mass flywheel. Service parts require production date verification—timing belts for pre-2007 engines are incompatible with post-2007 revisions due to tensioner redesign (PSA SIB-ENG-04-018).
The HMZ (EB2)'s primary reliability risk is timing belt tensioner degradation, with elevated incidence in high-mileage or stop-start environments. Internal PSA quality reports from 2006 noted a significant number of pre-2007 units requiring premature belt replacement, while UK DVSA records show timing-related failures contributing to MOT failures in high-mileage examples. Extended service intervals and thermal stress increase risk, making adherence to 8-year/120,000 km replacement critical.
Analysis derived from PSA technical bulletins (2004-2010) and UK DVSA failure statistics (2006-2012). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CITROEN HMZ-EB2.
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