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Q: CEL slow higher rpms

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My car is a DCT with JB4 tune and BMS intake. When I shifted at higher rpms my car sputtered and slowed down. The Check Engine Light came on the dashboard, so I turned off the engine and started it back up. Then everything was back to normal. I tried to run the stock tune and it bypassed the JB4 completely and the same problems occurred. Do you know what might be causing this?

Hello there, thank you for asking about your 2013 BMW 135i. The very first thing I would do is have the vehicle scanned for trouble codes, as sputtering and a Check Engine Light can be caused by a wide variety of symptoms. Retrieving the trouble codes can give a clue as to what the issue may be. You mention that you have had high performance aftermarket components installed; it may be possible that they are interfering with the stock engine performance or emission systems, and causing the check engine light to come on. If you want to have this checked by a certified mechanic, a technician from YourMechanic can come to your home or office to have the vehicle scanned for trouble codes.

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