The MTA is replacing 300 kaput horns on new $1.3 million subway cars running on the lettered lines, NYC Transit said.

Gunk from dirty tunnels was causing the horns to warble more than earlier models, sources said.

“It sounds like a shrill elephant,” one transit worker said.

After workers cleaned them, the horns weren’t adhering properly to trains, so transit officials are sending all 300 back to the contractor in South Carolina for replacements.