The knock sensor in your vehicle informs your ECU of dangerous detonation or pre-ignition, conditions that could severely damage your engine. Detonation occurs when something with the vehicle’s fuel or spark delivery is not quite right, creating a dangerous mix of air fuel ratio that could melt or break things.
Without the knock signal input from your Toyota 2JZ engine, the ECU will not know when detonation occurs. When this condition is left for several driving cycles, the ECU will trigger the Malfunction Indicator Lamp (MIL) which appears as a SERVICE ENGINE SOON or CHECK ENGINE LIGHT.
The specific description of the OBDII trouble code P0330 in our 1999 Lexus GS300 is Knock Sensor 2 Circuit Malfunction (Bank 2). This is known as Circuit B or the secondary knock sensor, which is located toward the rear of the engine. Unfortunately this means that one of two things has occurred, either your Bank 2 2JZ knock sensor has failed, or the wiring harness that leads to this sensor has a problem.
Either way if you are working with the engine in the car, this is not an easy process. You will be best served by using a two post lift, but if you are stuck using jackstands, make sure to be safe and secure the vehicle. For a few tips on how to work safely, check our guide here.
This knock sensor is Toyota part number 89615-12050 and it’s not an overly expensive part, however removing your old unit and installing a new one is very difficult. Our how to replace a 2JZ knock sensor guide shows you a slightly easier method to removing your knock sensor.
Symptoms of OBDII DTC P0330
- Sluggish acceleration
- Poor fuel economy
- Pinging or rattling under load
- Excessive emissions
How to Replace a 2JZ knock sensor
We’ll be removing the knock sensor from underneath the vehicle if you have a two post lift. The rear knock sensor is the one you’ll be replacing in our How to Replace a 2JZ knock sensor DIY article. Unfortunately most of the wiring harness, vacuum block and intake manifold blocks what little access you have to your knock sensor.
How difficult is this job? Well you’ll either be removing the top half of your intake manifold to reach this sensor or snaking your hand between a lot of moving parts to access this sensor. Let’s begin with removing the negative terminal on your battery for starters to prevent any electrical accidents.
From the bottom of your GS300 or 2JZ equipped vehicle, you should be able to see the intake manifold brace that mounts to the block.
Remove the two bolts that hold this brace if you can reach the rear knock sensor from the oil filter side. If you don’t have this brace, move on to the vacuum block located underneath your intake manifold. Disconnect the two pin engine harness from this vacuum block, and then loosen the 10mm nuts that hold the vacuum block to the intake manifold studs.
These nuts will allow you to loosen and move the vacuum block and gain the necessary room to wiggle an adjustable wrench over your Bank 2 knock sensor.
Pull off the black box and rotate it towards the 2JZ engine, this will give you some wiggle room behind the box. You must disconnect a engine harness mounting clip behind this vacuum block before you can proceed with our how to replace a 2JZ knock sensor guide.
This vacuum block controls the butterfly mechanism in your throttle body, do not disconnect your vacuum lines from this block during this process. The next part of our How to Replace a 2JZ knock sensor DIY article is accessing your knock sensor. Reach up and unplug your 2JZ knock sensor, and then you can undo the wiring harness ring.
You must first remove this wiring harness retainer from a metal mount on the engine.
Depress the top of this engine harness retaining ring, and then pull off your metal bracket. This will give you the clearance needed to undo the rear 2JZ knock sensor, and replace with your new one.
If you have another job that may require removal of your throttle body and / or intake manifold, take the P0330 check engine code with a grain of salt. You will need to unplug and disconnect your TPS as well as the intake snorkel and MAF to access the throttle body mounts on the side of your cylinder head. The 2JZGE intake manifold folds over your engine, and the removing the top half your intake manifold can aid you reaching your rear knock sensor.
Need to learn more about removing the top half of your intake manifold or the entire manifold itself? Check our guide here for our How To Remove a 2JZGE Intake Manifold for more details.
Once you get your bank 2 knock sensor replaced, use a scan tool to clear your OBDII trouble code of P0330 and test drive the vehicle. Have any questions about our How to Replace a 2JZ knock sensor DIY article? Leave them for us below!