Do I have an air leak in my 2010 Holden Barina's intake manifold?

This generation of Holden engines was prone to failure of the crankcase ventilation valve (PCV). When it failed, it caused a vacuum leak in the engine that could easily cause rough running and hard starting. It would also possibly trigger a check-engine light.

Depending on the model and year of the car, you might be able to fit a replacement PCV, but sometimes the solution was to replace the entire rocker cover assembly, which included the valve in question. In many cases, the valve failure was accompanied by a failed rocker cover gasket that leaked oil on to the spark plugs, making the car run even more erratically. Don’t be tempted to try a second-hand PCV from a wrecked Barina. The chances are every high that it’s PCV will be trashed, too.