H25A engine — SQ 2.5 (2.5L)
2.5L · 144-158 hp
Engine overview
Vehicles with this engine
Factory specifications
Values from the manufacturer documentation for this engine.
Engine (general)
| Engine code | H25A |
| Capacity | 2493 cc |
| Idle speed | 650 ± 50 rpm |
| Normal | 14.0 - 16.0 bar |
| Minimum | 13.0 bar |
| Differential limit between cylinders | < 1.0 bar |
| Oil pressure | 3.9-4.7 / 4000 bar/rpm |
| Idle speed | 750 ± 50 (800 ± 50) rpm |
Engine (petrol)
| Number of cylinders | 6 |
| Firing order | 1-6-5-4-3-2 |
| Timing stroboscopic (before TDC) | 5 ± 1 / 750 ± 50 °/rpm |
| Spark plugs (make and type) | NGK BKR6E-11 Denso K20PR-U11 |
| Spark plugs (make and type) | NGK IFR5J11 Denso SK16PR11 |
| Spark plug gap | 1.0 - 1.1 mm |
| Fuel pump pressure | 4.5 bar |
| Injection pressure/system pressure | 2.1 - 2.6 bar |
| CO at fast-idle speed | < 0.2 % |
| Fast-idle speed | 2500 - 2800 rpm |
| Lambda | 0.97 - 1.03 |
| Oil temperature during test | 80 °C |
| Closed-loop test at: | 625 - 800 rpm |
| Conditioning catalytic converter | 2 / 3000 min/rpm |
| CO exhaust gas | < 0.5 % |
| Firing order | 1 - 6 - 5 - 4 - 3 - 2 |
| CO exhaust gas | 0.8 - 1.3 / 750 %/rpm |
| CO adjustment screw | A |
| Conditioning catalytic converter | 0.5 / 2500-3000 min/rpm |
| Oil temperature during test | 85 °C |
| CO at fast-idle speed | < 0.3 % |
| Lambda change (Delta Lambda) | 0.03 |
| Closed-loop test at: | 550 - 1100 rpm |
| Malfunction rate engagement (Germany only) | Nr. 20 |
Cooling system
| Cap pressure | 1.1 bar |
| Thermostat opens at | 82 °C |
Electrical
| Battery | 28 / 36 / 48 / 54 Ah |
| Alternator | 60 / 70 / 80 A |
| Alternator | 60 / 70 / 85 A |
Capacities
| Engine sump, incl. filter | 5.5 l |
| Gearbox refill | 2.6 l |
| Gearbox refill | 2.5 l |
| Transfer box | 1.7 l |
| Differential, 4WD front | 1.0 l |
| Differential, 4WD rear | 2.2 l |
| Cooling system | 8.0 l |
| Air-conditioner refrigerant | 450 ± 50 g |
| Air-conditioner refrigerant | 400 ± 50 g |
| Air-conditioner compressor oil | 120 ml |
| Gearbox refill | 2.7 l |
Torque settings
| Cylinder head bolts — Stage 1 | 53 Nm |
| Cylinder head bolts — Stage 2 | 84 Nm |
| Cylinder head bolts — Stage 3 | 105 Nm |
| Cylinder head bolts — Stage 4 | 11 Nm |
| Spark plugs | 25 Nm |
| Manual transmission drain plug | 45 Nm |
| Automatic transmission drain plug | 23 Nm |
| Oxygen sensor | 45 Nm |
| Wheel nuts | 100 Nm |
| Front hub | 216 Nm |
Emissions
| Emission code | 70/220*2001/100A |
| Emission standard | Euro 3 |
| CO2 average | 245 g/km |
| CO | 0.391 g/km |
| HC | 0.040 g/km |
| NOx | 0.005 g/km |
| HC NOx | 0.045 g/km |
| CO2 average | 262 g/km |
| CO | 0.299 g/km |
| HC | 0.043 g/km |
| NOx | 0.001 g/km |
| HC NOx | 0.044 g/km |
Workshop procedures for this engine
Step-by-step procedures from the workshop database.
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TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
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The story behind TorqFix →Workshop data on this page last updated 22 Aug 2026.