2012 MERCEDES-BENZ S-Class M278 DE 40 LA/M157 V8 (W221)

Engine identity

Oils and fluids

Service and parts data

Common and chronic problems

• Air suspension wear
• Electrical system glitches
• Timing chain guides wear on certain engines

First checks

• Check air suspension spheres and compressor function
• Inspect timing chain condition on V6 and V8 engines
• Battery and electrical system health

Vor dem Teiletausch

• 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-specific engine offerings and emissions equipment differ between Europe, North America, and Asia.
• 2012 model year represents the final year of the W221 generation before the 2013 facelift introducing 9G-Tronic transmission.