Why is my Nissan hardbody speedometer not working?

The Nissan hardbody speedometer not working causes are faulty engine control unit or loose wires. You will come into many issues with an engine. A gasket may be loose and that needs to be tightened up quickly. You can have oil leaks and those need to be fixed as soon as possible. A spark plug may pop off, causing engine trouble. A dire problem is the engine overheating. This may lead to car fires and the vehicle exploding. There could be excessive oil use, requiring the oil to be changed quickly Your air filter needs to be changed every 15,000 to 30,000 miles. The coolant needs to be changed every 60,000 miles. The spark plugs need to be changed every 100,000 miles or so unless it's a copper one. A cooper spark plug needs to be changed every 30,000 miles or so.