Investigations on 1.3 μm DCPBH laser diodes under high electrical stress are reported. Leakage currents are identified by electro-and photoluminescence. Experiments on laser diodes with additional collector contacts to the n-InP floating layer show that blocking layer leakage is strongly enhanced by transistor action. The observed aging behavior is described. Excellent stability is observed for our diodes, more so after stress testing. It is found that stress test aging of diodes from moderate quality wafers, which typically still strongly levels off in time, is not caused by an increase in leakage current via the blocking layers, but by an increased leakage in and/or around the mesa. Though transistor action has a strong influence on device performance at high currents, thyristor breakover is shown to be absent in DCPBH-diodes: primarily due to lateral conduction in the blocking layers. Experimentally, thyristor breakover could be obtained by restricting the lateral conduction to about the channel width or less.