My 2002 Sequoia’s check engine light came on. Computer code is P0325. Cleared it cranked back up and the check engine light came back on. Is this some-thing Seafoam or a new Fuel Filter will fix. How difficult is it to access this sensor? Where is it located? Is there one or two sensors?
I’ve not seen anything that indicates that the knock sensor is defective. Do you see that from just a diagnostic trouble code (DTC)? I would want to check out the circuit to/from the knock sensor. What if it were just a bad connection, or a broken wire?
Seafoam won’t help a knock sensor. Fuel filter won’t help either. A Haynes manual will show where every sensor is and will help interpret the codes, or maybe just list them.
Seafoam fixes anything, just read the can 
As Hellokit stated, the code indicates a problem with the circuit wiring to the sensor. Most likely there is a connection problem at the sensor itself though it could be somewhere else also.
Thanks everyone for the input. Yes the P0325 is a trouble code that the Auto Zone Tech got when he connected my car to the computer. Today the plot thickened. The A/C is now making alot of noise. It sounds like a industrial fan when turned on high. The air out-put seems to be the same. Could these be related or am I just experiencing problem #2. It seems things do like to come in 3’s. I called about getting the sensor checked and the estimate was @ $1500.00. The Tech said they would have to take apart the motor to get to the sensor. If I don’t get this fixed could it damage my motor. I don’t really have that to spend on a motor right now. But I would hate to have to buy a new motor. Thanks everyone for taking time to reply, I greatly appreciate it. Have a great week.
These used to screw into the outside of the block. See if you can locate a picture of the sensor location.
Haynes Repair Manual - Toyota Tundra & Sequoia 2000 thru 2002 (I have an '01 Sequoia) states in Chapter 6 page 8;
Drain the engine coolant and remove upper and lower intake manifolds.
Disconnect knock sensor electrical connector.
Unscrew the knock sensor with a deep socket.
Installation is the reverse of removal, be sure to torque to specs (which is 33 ft/lbs).
Never having removed and reinstalled the upper and lower intake manifolds I can’t say whether the estimate is reasonable or not. I’d certainly try to rule out other causes before changing out the knock sensor and finding out the code is still showing up.
On the AC fan, unrelated to code. My Sequoia when set on “Auto” the fan finds a speed that resonates and is quite loud. I adjust the speed either up or down a bit and it quiets down. Likely a bearing in the fan motor is getting old and loose and may need to be replaced someday. For the moment changing the speeds works on mine.
On running the motor as is. The Sequoia is set up for use of regular 87 octane fuel. Are you running regular? Are you hearing any knocks and pings from pre-ignition? In the old days engine knock was pretty common and I know the sound, kind of like random marbles running around under the hood.
If you are not hearing any knocking you should be OK. If you do any trailering, drive in the mountains with lots of big hills, or drive in a very hot climate then you might just move up to plus at 89 octane in those circumstances. Your motor should be fine as long as you are not hearing any knocking.
If your state has an inspection system you’ll need to get the “check engine” light off to pass inspection. This should give some time to find out the exact problem and get it corrected.
First off, A big thank you to everyone that helped trouble shoot this. I had to post what the mechanic found. Chewed wires. It seems the squirrels in my yard got tired of birdseed and decided to try chewing up my vehicle. They chewed through the plug that connects to the knock sensor.