The U1000 and U1001 mean that there is no communication between the engine control unit and another control units that are part of the CAN system (Controller Area Network) or that at some point there was no communication. Before do any repairs with the U1000 and U1001 codes, the factory recommend repairing any other problems in the car. Nissan has release service bulletins for this problem. A common cause with Nissan vehicles is the poor harness ground connection at the engine compartment and the ground connection behind the dash. Clean and resecure harness ground connection and reset engine light. symptoms Engine Light ON (or Service Engine Soon Warning Light) Possible causes Controller Area Network (CAN) communication harness is open or shorted Faulty Engine Control Module (ECM) Poor harness ground connection. Searches related to u1001 nissan altima u1001 can comm circuit nissan nissan code u1000 u1000 u1001 nissan pathfinder u1001 nissan 350z nissan p1212 u1001 code infiniti u1001 nissan quest 2004 nissan dtc p1212
