Coking phenomena and erosive damage are well-known aging effects that occur in fuel-injection nozzles and deteriorate the engine performance of direct injection engines. This paper presents a method to compensate for these effects by utilizing a closed-loop control of desired injection characteristics. First, a control-oriented simulation model of the entire fuel injection system is presented that describes the injection rate at different working conditions. The actual state of aging is then estimated from cycle-to-cycle by using a linear quadratic state estimator and feedback from a pressure sensor. The closed-loop controller utilizes important injection characteristics like the injected fuel mass, the start of injection (SOI), and duration of injection (DOI) of the predicted injection rate. Thus, the nominal injection pressure and energizing signal are set in such a way that the desired injection features are obtained. The method is successfully applied and tested on an injection measurement rig, and experimental results show the great potential in improving the injection accuracy. This makes the proposed controller particularly interesting for all applications that require a long lifetime, such as heavy-duty or marine engines.