An engine system includes an air intake system, an engine cylinder, a piston, an exhaust system, and an in-cylinder pressure sensor fluidly connected to the engine cylinder. The piston is movable within the engine cylinder during a combustion cycle, and the engine cylinder is fluidly connected to the air intake system via an intake port and an intake valve. The exhaust system is fluidly connected to the engine cylinder via an exhaust port and an exhaust valve. The in-cylinder pressure sensor is fluidly connected to the air intake system via an in-cylinder pressure sensor cooling line.