The effect of extrinsic background doping on the transient enhancement of dopant diffusion for an ion‐implanted dopant is investigated to gain insight into the role of point defect charge states. The transient effect is found to be greatly increased for extrinsic background doping of the same type as the implanted ion, and reduced for background doping of the opposite type. Analysis of the relative enhancements for boron and phosphorous allows the position of the donor and acceptor levels for the silicon self‐interstitial to be extracted. The results are in good agreement with earlier work based on extrinsic oxidation‐enhanced diffusion.