The Porsche M 48.40 is a 2,480 cc, water‑cooled inline‑four petrol engine produced between 1997 and 2000. It featured Bosch Motronic 5.2 electronic fuel injection, dual overhead camshafts (DOHC), and a 16‑valve layout. In the 968 it delivered 143 kW (194 PS) and 245 Nm of torque, with a redline of 6,800 rpm.
Fitted exclusively to late — production European — spec Porsche 968 models, the M 48.40 was engineered for refined performance and full compliance with Euro 2 emissions s…
Production years 1997–2000 meet Euro 2 emissions standards under EU Directive 94/12/EC (VCA UK Type Approval #VCA/EMS/9685).
The Porsche M 48.40 is a 2,480 cc inline‑four petrol engine engineered for the final-year Porsche 968 (1997–2000). It combines Bosch Motronic 5.2 engine management with DOHC architecture to deliver smooth high-revving performance and compliance with Euro 2 emissions. Designed as a minor evolution of the M 44 series, it prioritizes emissions compliance and drivability over mechanical innovation.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,480 cc | |
Fuel type | Petrol (Unleaded) | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 95.0 mm × 87.3 mm | |
Power output | 143 kW (194 PS) | |
Torque | 245 Nm @ 4,100 rpm | |
Fuel system | Bosch Motronic 5.2 sequential electronic injection | |
Emissions standard | Euro 2 | |
Compression ratio | 10.2:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain-driven DOHC with hydraulic tensioner | |
Oil type | Porsche Longlife 10W‑40 (ACEA A3/B3) | |
Dry weight | 141 kg |
The Porsche M 48.40 was used exclusively in Porsche's 968 platform with front-engine, rear-transaxle longitudinal mounting and no external licensing. This engine replaced the M 44.04 in late European production and featured updated Motronic 5.2 ECU and revised emissions calibration for Euro 2 compliance. All adaptations are documented in OEM technical bulletins.
The M 48.40's primary reliability risk is hydraulic timing chain tensioner seal degradation, with elevated incidence in high-mileage examples exceeding 100,000 km. Porsche field data from 1999 indicated over 14 % of engines required timing system inspection before 120,000 km, while UK DVSA MOT records correlate degraded lambda sensors with catalyst failure and emissions non-compliance. Extended oil change intervals accelerate tensioner wear, making oil quality and service adherence critical.
Analysis derived from Porsche technical bulletins (1997–2000) and UK DVSA failure statistics (2000–2023). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The M 48.40 offers refined performance but requires vigilant maintenance. The hydraulic timing tensioner is its main weakness—inspect after 100,000 km. Using correct ACEA A3/B3 oil and replacing lambda sensors at 80,000 km ensures longevity. Well-maintained examples can exceed 200,000 km without major issues.
Top issues include hydraulic timing tensioner wear, lambda sensor degradation, cam cover oil leaks, and rear coolant flange cracking. All are documented in Porsche service bulletins (e.g., 968/03/98). The interference design means timing issues can cause catastrophic failure if ignored.
Exclusively the European-spec Porsche 968 (1997–2000) in Coupé and Club Sport forms. It was the final inline-four used by Porsche in a production car, replacing the M 44.04. No US or external-brand applications exist. All feature front-engine, rear-transaxle layout.
Yes—common upgrades include high-flow intake, performance exhaust, and ECU remap. Stage 1 typically yields 210–220 PS. However, the stock internals limit safe output; going beyond 240 PS risks rod bearing wear. Forced induction is rare and requires extensive modification.
Approximately 12.9 L/100km (city) and 8.5 L/100km (highway), or ~28 mpg UK combined. Aggressive driving can exceed 15 L/100km. The Bosch Motronic 5.2 system is efficient for its era but less so than modern direct injection.
Yes. The M 48.40 is an interference engine—pistons and valves occupy the same space if timing fails. A worn tensioner or broken chain can cause severe internal damage. Immediate attention to timing rattle is essential to prevent engine destruction.
Porsche specifies 10W‑40 oil meeting ACEA A3/B3 standards (e.g., Porsche Longlife 10W-40). Modern low-SAPS or C3 oils are not recommended. Change oil every 10,000 km to protect the hydraulic tensioner and valvetrain.
Comprehensive technical documentation and regulatory references
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Regulation (EC) No 715/2007
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