| Cause | Description | |-------|-------------| | | You installed a mod (e.g., realism mod, custom map pack) that altered or added .IWD files. | | Manual file tampering | You edited an .IWD file (even innocently, like a sound or HUD change). | | Corrupted game files | A bad download, hard drive error, or incomplete update corrupted an .IWD . | | Different game version | Server runs a specific patch (e.g., 1.2, 1.3, 1.01) and your client’s base files differ. | | PunkBuster strictness | Servers with PB enabled enforce pure client checks more aggressively. | | Outdated anti-cheat | Rare, but an old PunkBuster installation can misflag files. |
The “Impure client detected” error is a , not a bug. It protects server integrity. Most cases are solved by cleaning the main folder of stray mod files. If you want to play with mods, seek servers that explicitly allow them ( cl_pure 0 ). impure client detected call of duty 2