A diagnostic system for an electric power steering system, comprising: a first microprocessor configured to receive first and second signals (MPS_Sin, MPS_Cos) from first and second position sensors (100, 110), respectively, disposed in a motor of the electric power steering system, the first and second signals (MPS_Sin, MPS_Cos) being indicative of a relative rotational position of a magnet disposed on a rotatable shaft of the motor, the first microprocessor further configured to determine a first relative position value indicating the relative rotational position of the rotatable shaft at a first time based on the first and second signals (MPS_Sin, MPS_Cos); third and fourth position sensors (200, 210) disposed proximate to the rotatable shaft and outside of the motor, the third and fourth position sensors (200, 210) configured to generate third and fourth signals (TC_Sin, TC_Cos), respectively, indicative of the relative rotational position of the magnet on the rotatable shaft; a second microprocessor configured to receive the third and fourth signals (TC Sin, TC Cos) and to determine a second relative position value indicating the relative rotational position of the rotatable shaft at the first time based on the third and fourth signals (TC_Sin. TC_Cos); the second microprocessor further configured to send the second relative position value to the first microprocessor; and the first microprocessor further configured to determine a difference between the first relative position value and the second relative position value; and the first microprocessor further configured to store a diagnostic value in a memory device indicative of whether the second relative position value is acceptable based on the difference between the first relative position value and the second relative position value. a first microprocessor configured to receive first and second signals (MPS_Sin, MPS_Cos) from first and second position sensors (100, 110), respectively, disposed in a motor of the electric power steering system, the first and second signals (MPS_Sin, MPS_Cos) being indicative of a relative rotational position of a magnet disposed on a rotatable shaft of the motor, the first microprocessor further configured to determine a first relative position value indicating the relative rotational position of the rotatable shaft at a first time based on the first and second signals (MPS_Sin, MPS_Cos); third and fourth position sensors (200, 210) disposed proximate to the rotatable shaft and outside of the motor, the third and fourth position sensors (200, 210) configured to generate third and fourth signals (TC_Sin, TC_Cos), respectively, indicative of the relative rotational position of the magnet on the rotatable shaft; a second microprocessor configured to receive the third and fourth signals (TC Sin, TC Cos) and to determine a second relative position value indicating the relative rotational position of the rotatable shaft at the first time based on the third and fourth signals (TC_Sin. TC_Cos); the second microprocessor further configured to send the second relative position value to the first microprocessor; and the first microprocessor further configured to determine a difference between the first relative position value and the second relative position value; and the first microprocessor further configured to store a diagnostic value in a memory device indicative of whether the second relative position value is acceptable based on the difference between the first relative position value and the second relative position value.