The answer to 'my pipe repair smells bad' is that a foul odor coming from a pipe repair is a common issue that can have several underlying causes. The most likely reasons are incomplete sealing of the repair, a failure to properly clean the pipes before the repair, or the use of low-quality materials that are now releasing unpleasant smells. This can happen with both DIY and professional pipe repairs.
To address the issue, first inspect the repair site for any gaps or cracks that may be allowing sewer gases to escape. You can try sealing these with a silicone-based caulk or sealant. If the smell persists, you may need to disassemble the repair and thoroughly clean the pipes before reassembling with new, high-quality materials. In some cases, the entire section of pipe may need to be replaced to fully resolve the odor problem.