Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › 2008 Chevrolet Impala LT Reduced Power Mode issue › Reply To: 2008 Chevrolet Impala LT Reduced Power Mode issue March 19, 2020 at 8:36 pm #953415 Richard KirshyParticipant These would lead me to test the crank position sensor… 1) The car shudders like the engine is chugging. 2) The tachometer cuts out completely, reads 0. 3) The engine announces Reduced Power Mode and the CEL comes on.