no check engine light but scan picking the code U1000 CAN COMM CIRCUIT

Question

2001 Nissan x trail check engine light came on reading 2 codes on the scan ,1 for the ignition coil and the other for can comm circuit, changed the faulty coil pack and erased the check engine light it disappeared but the scan still reading code U1000 CAN COMM Circuit but there is no check engine light.