A number of Impala owners have complained about a clicking or clunking sound when turning the steering wheel.  More often, it is felt through the steering wheel vice actually being heard.

This problem has been attributed to the intermediate steering shaft (ISS) and is usually resolved by replacing it.

This problem plagues a number of GM vehicles including, Cavalier, Intrigue, Aurora, Bonneville, Sunfire, Regal, LeSabre, DeVille, Seville.  Unfortunately this also affects the 2000-2002 Chevrolet Impala and Monte Carlo.

What is the ISS?  It connects the steering column to the rack and pinion and goes through the firewall.

Insufficiant lubrication is the cause of the noise or clunk.  GM has come out with a fix.  You need the lubrication kit, Kit GM P/N 26098237.  This kit consists of a syringe of lubricant and a rubber plug.  The repair goes like this:
  1. Remove the ISS.
  2. Fully extend the shaft.
  3. Apply contents of syringe into yoke opening.
  4. Use rubber stopper to plug up opening.
  5. Collapse the shaft and extend it a few times.
  6. Remove the plug and inspect the shaft splines for a coating of grease.

A TSB should be forthcoming.