A connecting rod bearing connects engine pistons to the crankshaft, converting reciprocating motion into rotating motion. When there are problems with engine bearings, the vehicle will demonstrate a few of symptoms. A bad rod bearing will eventually destroy an engine. 

Symptoms of Faulty Engine Bearings: 

1.Knocking Noise From Engine: If you hear knocking sounds while the engine is running, especially during cold starts, this is a good indicator that your engine has bad main bearings. If you hear a deeper noise, it indicates a problem with the main engine bearing rather than a rod bearing.   
2.Oil Light: A bad rod bearing can cause the oil pressure to be lower. The less oil between the bearing and its cover results in metal-on-metal contact. 

Diagnosis:
Visual Inspection: Firstly, raise the front wheels with a jack. Then remove the drainage bolt from the oil pan with a wrench to drain the oil off. If the oil contains metal shavings, it demonstrates that is is a warning sign of faulty bearing.