We investigate the origin of the apparently reduced recombination parameter J(0) of highly doped regions obtained from e.g. QSSPC lifetime measurements at high injection densities as well as the influence of recombination at bulk defects on the recently updated J(0)-analysis of QSSPC measurements in the Sinton lifetime tester software. Using the example of crystalline silicon, we show that the frequently observed reduction and underestimation of J(0), which is strongly pronounced at high injection levels, originate from neglecting the finite carrier diffusion coefficient. This work presents an analysis taking into account the finite carrier diffusion coefficient and thus enabling to evaluate charge carrier lifetime data at high injection levels leading to strongly increased consistency of the determined J(0). Furthermore, we give a simple correction term for the recently published analysis leading to a total independence of a reasonably injection-independent Shockley-Read-Hall (SRH)-lifetime in the substrate. Combining the proposed methods, the determination of J(0) from numerically simulated lifetime-data is accurate within 3% of the input J(0)=100 fA/cm(2) over an injection range of 10(14)-3.10(16) cm(-3). The application of the proposed method to measured data of crystalline silicon devices is in excellent agreement with the simulations and shows a strongly improved linearity and thus constant extracted J(0) compared to the former and recently published methods, which underestimate J(0) at high injection levels, nearly independently from doping type and -level of the substrate. The new and simple method is implemented in a spreadsheet calculator enabling fast and robust data evaluation similar to the Sinton lifetime tester software. (C) 2015 Elsevier B.V. All rights reserved.