N63T - CHECK ENGINE LIGHT (MIL) ON AFTER A HOT ENGINE RESTART. The check engine light (MIL) may come on after a hot engine restart. When this happens the engine may have a longer cranking time before starting. The following faults are stored in the DME: 20A504 - Turbocharger coolant pump, actuation: Line disconnection 133011 - Valvetronic, supply voltage: Malfunction 133013 - Valvetronic 2, supply voltage: Malfunction 1F0515 - Valvetronic, supply voltage: Line disconnection 1F050F - Valvetronic 2, supply voltage: Line disconnection The ISTA test plans are inconclusive as the circuits check as good and this problem may be difficult to reproduce. This problem is caused by air in the cooling system which tends to collect in the area of the turbocharger electric coolant pump. When the engine is shut off the turbocharger coolant pump impeller continues to spin down in the air pocket. This subsequently generates a voltage that is fed back to the DME causing the faults to be stored.
