Is your Check Engine light on, and you have a code P0327 or P0332, but you don’t know what that means?
Our mechanic explains what these “Knock Sensor Circuit Low Input” OBD2 codes mean, what can cause them, and shows you how to diagnose your car’s knock sensors by reading their signals and inspecting their wiring harnesses in this video. Watch now:
Check Engine Light? Knock Sensor Low Input – Code P0327 P0332
What are codes P0327 and P0332, and what do they mean?
P0327, “Knock Sensor 1 Circuit Low Input (Bank 1),” and P0332, “Knock Sensor 1 Circuit Low Input (Bank 2),” usually mean your knock sensors are bad—they’re malfunctioning—and need to be replaced.
What is engine knock?
During a vehicle’s combustion process, which you can read about in “How to diagnose a misfire: Expert help from our mechanics,” if a spark plug ignites the fuel too early, or if the fuel used in a vehicle is incorrect, that can create too much pressure inside the engine, which results in an internal explosion outside of the normal combustion process. This engine knock results in a knocking or tapping sound.
The purpose of knock sensors is to monitor and alert your car’s computer, or the powertrain control module (PCM), if engine knocking occurs.
How serious are P0327 and P0332—can I drive with these codes?
If left unaddressed, engine knocking can damage your engine and lead to more costly repairs, so it’s best to resolve a P0327 or P0332 as soon as possible and avoid driving with it.
What are typical P0327 and P0332 code symptoms?
- Your Check Engine light is on
- Drivability issues can include difficulty accelerating, unsteady RPM, or loss of engine power
- A knocking or tapping sound
What causes a P0327 or P0332 code?
- Bad or faulty knock sensor
- Faulty, open, or shorted knock sensor circuit wiring
- Corroded knock sensor wire connector
How do I diagnose and fix P0327 or P0332?
In the video above, the knock sensors in the vehicle our mechanic works on are located under the intake, so he removes the intake to access them.
Test your knock sensors’ data readings
- With the meter set to AC voltage for the range millivolts, put one of the leads on one of the knock sensors and ground the other lead.
- Use a screwdriver to tap near the sensors and watch the meter reading while you do this.
- If the readings don’t change at all while you do this, that means the problem triggering a P0327 or 332 is an open circuit in the knock sensor.
- You can also check the knock sensor’s resistance with a multimeter (2:19). Set the meter to ohms (which looks like a little horseshoe), place one of the leads on the ground, and the other on one of the knock sensors.
- If your meter’s reading says, “OL,” that means there’s an open circuit in one of the sensors, which means that knock sensor isn’t working.
Check your knock sensor wire connectors for corrosion
- If a knock sensor connector is corroded, you’ll need to replace both the sensor itself and the wire.
- After inspecting the knock sensors, our mechanic recommends replacing your wiring harness at the same time you replace other parts in this area, such as a bad knock sensor that needs to be replaced. Wiring harnesses aren’t expensive parts, which makes it worth replacing them since they become brittle over time.
Mechanic tip: Be careful when replacing knock sensors because they’re sensitive—you don’t want to accidentally drop and damage them.
How to Replace Knock Sensors
Once you’ve determined what triggered a P0327 or P0332 in your car, and replaced any bad parts, clear the code, and drive your car to make sure everything’s running correctly.