Abstract Analyzing single-dish and very long baseline interferometry radio, as well as Fermi Large Area Telescope γ-ray observations, we explained the three major flares in the γ-ray light curve of FSRQ J1048+7143 with the spin–orbit precession of the dominant mass black hole in a supermassive black hole binary system. Here, we report on the detection of a fourth γ-ray flare from J1048+7143, appearing in the time interval that was predicted in our previous work. Including this new flare, we constrained the mass ratio into a narrow range of 0.062 < q < 0.088, and consequently we were able to further constrain the parameters of the hypothetical supermassive binary black hole at the heart of J1048+7143. We predict the occurrence of the fifth major γ-ray flare that would appear only if the jet will still lay close to our line of sight. The fourth major γ-ray flare also shows the two-subflare structure, further strengthening our scenario in which the occurrence of the subflares is the signature of the precession of a spine–sheath jet structure that quasiperiodically interacts with a proton target, e.g., clouds in the broad-line region.