The spectra and the pulse decay of the injection luminescence are measured on LPE‐GaP:N diodes as a function of the stress time and the forward current under test. For the case of high injections the light output and the decay times are determined separately for both, n‐ and p‐regions. The stress‐time dependences of the total light output of the different decay times deviate between each other. These effects can be explained by the common influence of the Zn profile change itself, by a profile‐change induced injection shift, and by the different volume degradation of both, neutral regions and a compensated interlayer.