BMW M5: S63TU Fuel Injector Failure and Misfire (pre-2014 injectors)

The F10 M5's 4.4 twin-turbo V8 suffered a bad run of fuel injectors on early cars; BMW revised the injector for 2014 but dealers commonly replaced them one at a time as each failed rather than as a set. A failing injector misfires, washes the bore with fuel and can take an ignition coil or catalytic converter with it if ignored. Cars still on a mixed set of early injectors keep failing one by one.

• Misfire or rough running, especially at idle when warm
• Engine management light with injector or misfire codes
• Fuel smell after start-up
• Uneven, lumpy idle after short trips

Go through the service history looking for injector replacements — count how many and when; one or two replaced recently suggests the rest of an early set is still in the engine. Listen for misfire at idle from cold start through to warm. Ask whether the injectors were ever done as a full set of eight. If a workshop inspection is possible: read misfire counters and injector correction values per cylinder on a BMW-specific scan tool.

Parts involved: Fuel injector.

$800 to $5,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “How many injectors have been replaced, and were they done as a set?”
• “Any misfires or rough idle since the last service?”
• “Was injector work done under warranty or goodwill?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.