A method of operating an engine includes determining a relative position between a first camshaft and a second camshaft during a startup event of the engine when the first camshaft is at a first home position and the second camshaft is at a second home position. The first home position is a first preset angular position of the first camshaft relative to a crankshaft. The second home position is a second preset angular position of the second camshaft relative to the crankshaft when the engine is in an OFF state. The method includes generating a first estimate of the first home position. The method also includes diagnosing a mis-build of the engine based on the relative position, the first estimate and a second estimate of the second home position.