Hybrid drive faults and false warning lights
BMW has issued bulletins for the plug-in hybrid system the M5 shares with the XM and other BMW plug-in hybrids: sporadic resets of the power electronics that can stop the car starting or engaging a gear, with drivetrain warnings (SIB 61 03 26; the fix is a software update, and BMW says replacing parts will not help); overheating of the electric drive that cuts electric power, traced to low coolant or a blockage in its separate low-temperature cooling circuit (SIB 24 03 24); and charging-unit software that turns on the check-engine light while charging works normally (SIBs 61 19 25, 61 22 25 and 61 23 25). Owners discuss drivetrain warnings on the M5 forum. The documented fixes are software updates and cooling checks, done free under the 4-year, 50,000-mile warranty; we found no out-of-warranty price for the hybrid electronics.
How to check
Ask a BMW dealer to confirm the software level and scan for stored hybrid and charging faults, drive the car in electric and hybrid modes, and charge it on a Level 2 charger before you buy.
