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 standards. Emissions control was achieved via a three‑way catalytic converter, sequential fuel injection, and precise lambda control under EU Directive 94/12/EC.
One documented concern is hydraulic timing chain tensioner seal degradation, which can lead to loss of tension and potential interference damage. This issue is referenced in Porsche Technical Bulletin 968/03/98, which recommends inspection of tensioner function during 100,000 km service intervals.
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 DOHC layout provides smooth high-RPM power but relies on a hydraulic timing chain tensioner prone to internal seal wear after 100,000 km. Use only ACEA A3/B3–compliant 10W-40 oil (e.g., Porsche Longlife) and change every 10,000 km to maintain tensioner function. Bosch Motronic 5.2 requires healthy lambda sensors—replace every 80,000 km to prevent rich running and catalyst damage. The engine is an interference design: timing system failure can cause catastrophic valve-piston contact. Inspect tensioner per Porsche SIB 968/03/98.
Oil Specs: Requires ACEA A3/B3 10W-40 (Porsche Longlife) per PT‑1999. Not compatible with modern low-SAPS or C3 oils.
Emissions: Euro 2 certification confirmed for all 1997–2000 M 48.40 engines (EU Directive 94/12/EC, VCA Type Approval #VCA/EMS/9685).
Power Ratings: Measured under DIN 70020. Output consistent across all 968 variants (Porsche PT‑1999).
Porsche Technical Information System (TIS): Docs P968‑M4840, SIB 968/03/98
EU Directive 94/12/EC on vehicle emissions
Porsche Parts Catalogue (ETK) 2000 Edition
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.
Locate the engine code stamped on the left-side crankcase near the oil filter housing—“M48/40” confirms this variant. The 968 features a distinctive transaxle layout with rear-mounted gearbox. M 48.40 is differentiated from earlier M 44 engines by Bosch Motronic 5.2 ECU (part #0 261 200 578) and full Euro 2 compliance with no secondary air pump. Do not confuse with M 44.04 (1996–1997) or US-spec M 44/40 (detuned, with air injection).
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.
Find answers to most commonly asked questions about PORSCHE M-48-40.
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