lower gear when trying to shift up or selects a lower gear than intended while shifting down (as in a motorbike sequential manual transmission), the engine will be forced to rapidly rev-up to match the speed of the drivetrain. If this happens while the engine is at high RPMs, it may dramatically exceed the redline. For example, if the operator is driving close to redline in 3rd gear and attempts to shift to 4th gear but unintentionally puts the car in 2nd by mistake, the transmission will be spinning much faster than the engine, and when the clutch is released the engine's rpm will increase rapidly. It will lead to a rough and very noticeable engine braking, and likely engine damage. This is often known as a "money shift" because of the likelihood of engine damage and the expense of fixing the engine. Redlining in a diesel engine can be caused by the engine receiving fuel from an unintended source, such as flammable vapour in the intake air, or a broken oil seal in a turbocharger. This is known as diesel engine runaway, and can be stopped by blocking the air intake, or opening the decompression valve. See also Power band References Redline