Nissan Repair: 2001 Nissan Altima loosing power, nissan altima, knock sensor

Question
This car was loosing power at various times.I took it to my mechanic yesterday, he called and said the computer indicated it was the Knock Sensor which he replaced.He said after installing the Sensor he test drove it about 10 miles with no problem. I picked the car up yesterday evening, it did the same thing two times last night and one time this morning. when it acts up the dash gauges dims and sometimes the speedometer will show 50 miles per hour and the car will be setting still. the car never shuts down or off, this problem happens night or daytime.
Hope you can help me.
Thanks

Answer
Billy,

Have the charging system checked for proper alternator operation and that the battery is good.  If these are fine then remove the instrument cluster and clean the harness connection and the harness and reinstall.  Autozone or Checker will check the codes and charging system for free.