Nissan Repair: 1996 Nissan Altima knock sensor problem, nissan altima, gas mileage

Question
Hi,

I won a 1996 Nissan Altima. The cars engine light on the dash board was on for the last couple days. So i took it to a computer diagnostic center and the computer reported the following code and description:

P 0325 Knock sensor problem ( bank #1 )

What does that exactly mean?
My knowledge on cars is a big 0. the mechanic gave an estimate of $400. is it reasonable or can I shop around.
My gas mileage for the past couple years is pretty low ( about 14 mpg). Could the low gas mileage be because of this problem.

Thanks in advance,
Ragu

Answer
Ragu,

The knock sensor needs to be replaced and that should correct the mileage problem. It is a pain to get to so that is why the cost.  If I was you I would ask two other shops for estimates and then make your decision.  Cost is around $350 to get it done depending on the shop rate at the garage you go to.