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Q: Engine malfunction light, reduced engine power, engine powered down

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I was driving around 55 mph and the engine malfunction light came on, plus the warning message engine malfunction reduced engine power displayed. After this, the engine powered down. I was able to maneuver the car off the freeway and get it to my house. This problem has been recurring many times. This last time the car had to be towed to my mechanic’s shop. He was not able to duplicate the failure, so he wasn’t able to diagnose it. Would you please give me your assessment of this problem and what needs to be done to repair it?

A: Hi there. There are a lot of things that ca...

Hi there. There are a lot of things that can cause this on your 2012 BMW M5. I usually start by scanning the computer for codes to see what comes up. If there are not codes then I load test the alternator and the battery to see if they are failing. Low voltage in the electrical system will cause this. If that is fine, then it is usually caused by a failing throttle body. I have seen a lot of these fail due to the motors in them hanging up. If the problem is only happening intermittently, this can make the issue hard to duplicate, but you can still have tests done on the car. If you are going to have this fixed, consider YourMechanic, as a certified mechanic can come to your home or office to test the vehicle and diagnose the Engine Malfunction Light.

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