Q45 Knock Sensors
By: Wes Stinson
A common problem that has plagued many Nissan and Infiniti vehicles is problems with the knock sensors (also called KS).
Bad KS will not throw a CEL (Check Engine Light). Symptoms include loss or poor acceleration and can also cause bucking/jerking problems. Generally, knock sensors do not cause the vehicle to stall or idle rough, if you are experiencing that it is most likely something different.
To check and see if you have bad knock sensors, you must remove your ECU and check the trouble codes. This is the easiest way to diagnose, because if your knock sensors are even questionable it will throw a code in the ECU. It is outlined in the article below how to check ECU codes. Knock sensor code is #34. Of course, if you do not feel comfortable doing this you can take your vehicle to any Nissan or Infiniti dealership or specialty shop and they can scan the codes.
If you have a post 96 Q45 you can take it to any shop that has a code scanner (most shops have these) and they can determine if it is the knock sensors. Autozone also scans diagnostic codes for free.
If you find out you have bad knock sensors, you must remove the intake manifold to replace them. Q45’s have one (2) knock sensors. It is generally recommended that you replace its harness as well, as the connectors and wires become brittle over time.
The good news is that all knock sensors on basically every Nissan and Infiniti vehicle uses the same knock sensor, part number 22060-300P0. Many times you can go to eBay and type in “Nissan knock” and get them from $60-$90. Dealership prices are usually about $120-$150 per knock sensor.