Guidance thruster

From Memory Alpha, the free Star Trek reference

Guidance thrusters are starship components, located each of a ship's nacelles. These components appear to be separate in function from a starship's main thrusters.

The Jem'Hadar fighter discovered by the crew of Deep Space 9 on Torga IV, in 2373, was found in excellent condition, save a crushed guidance thruster – or comparable Dominion component. (DS9: "The Ship") During a later engagement with the USS Centaur, the Jem'Hadar ship was hit and lost one of its guidance thrusters. (DS9: "A Time to Stand")

While preparing for Operation Return in 2374, the USS Cortéz was forced to fall back for repairs after having a continued problem stabilizing the guidance thrusters in the ships port nacelle. (DS9: "Sacrifice of Angels")