2004 BMW Z4 M54B25/M54B30 (E85/E86)

Engine identity

Oils and fluids

Service and parts data

Common and chronic problems

• Cooling system issues (water pump, thermostat)
• VANOS system failure
• Convertible top mechanism wear (roadster)

First checks

• Inspect cooling system integrity
• Check VANOS and timing chain condition
• Verify convertible top function (roadster only)

Before replacing parts

• Save fault codes and freeze-frame data before clearing anything.
• Check engine oil, coolant and transmission fluid using the correct temperature and service procedure.
• Verify power, ground, connectors, hoses, leaks and live data before replacing expensive parts.

Important notes

• Market variations exist for engine and transmission availability; base roadster models commonly have M54 inline-6 engines, European coupe markets include high-performance S54 variant.
• Oil capacity includes typical filter replacement service-fill volume.