P0331 OBD Error Code: Problem & Solutions

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OBD-II Code P0331 Powertrain Control Module (PCM) failure is defined as a Knock Sensor 2 Circuit Range/Performance. It indicates that PCM has detected a voltage input reading in the knock sensor circuit for a particular cylinder that is not within a predetermined manufacturer’s limit. Due to this trouble code you may start confronting problems like audible knocking from the engine compartment, lack of power and some degree of hesitation upon acceleration. Keep in mind these problems don’t get over by time unless rectified.

Error code P0331 is technically described as Knock sensor (KS) 2, bank 2 -range/performance problem. This means the PCM has detected a problem with the knock sensor or its circuit. Some vehicles may be equipped with two knock sensors. Code P0331 pertains to the sensor on bank 2 (the opposite side of the engine where the #1 cylinder is located). The knock sensor detects vibration upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. When this voltage goes outside a calibrated level a DTC will set. The P0331 code means that the Knock Sensor is not working properly. Problems with the knock sensor will not cause engine performance problems but replacing the knock sensor usually takes care of the problem.

The sensor signal wire informs the PCM when a knock occurs and in what degree of severity. The PCM will retard the spark timing to avoid pre-detonation. If the PCM senses that the knock is severe and cannot be eliminated by retarding the spark timing, P0331 may set.

What causes the problem of Knock Sensor 2 Circuit Range/Performance?

• Knock sensor failure
• Flawed Knock sensor (KS) connector
• Knock sensor circuit is open or shorted to ground
• Knock sensor circuit is shorted to voltage
• Knock sensor connectors has moisture in it.
• Inaccurate fuel octane
• PCM failure (Rare)

1. Knock Sensor - A perfect knock sensor is very essential for the smooth running of your vehicle as knock sensor is responsible for making the PCM aware of unexpected engine noises primarily caused by an incorrect air/fuel mixture that leads to abnormal cylinder detonation. So, always make sure it should not be faulty.
2. Knock Sensor Connector - Knock sensor connector is an essential replacement item for restoring proper engine functioning as knock (detonation) sensor connector effectively relays electrical signals to the electronic control unit. If you ever discover it faulty, replace it as soon as possible because it may be a small component but it could be the main reason for any trouble code.
3. Spark Plugs - A spark plug is the starting point for combustion in your engine. Though spark plug is a seemingly simple device, it is tasked with a couple of very different and critical jobs. If you want your automobile to run smoothly always replace the faulty spark plugs in no time.
4. PCM - A powertrain control module, abbreviated PCM, is an automotive component, a control unit, used on motor vehicles. It is generally a combined control unit, consisting of the engine control unit (ECU) and the transmission control unit (TCU). It is very rare that your PCM fails but if it is failed then kindly repair or replace it immediately for proper functioning of your vehicle.

Below are the common symptoms for the code P0331. If you experience below mentioned symptoms please bring your vehicle to a reputable repair facility.

• Detectable knocking from the engine compartment
• Pinging from engine at the time of acceleration
• MIL (Malfunction Indicator Lamp) illumination

If you hear a heavy knocking in your vehicle, it could be an indication that the rod bearings are worn and in danger of seizing. If your vehicle has stored a P0331 code because it has a faulty knock sensor, the PCM will not be able to adjust for engine knock, and further engine damage can occur. It is possible that this code may be fixed by simply cleaning corrosion from the knock sensor connectors and ensuring that there is no moisture in the connectors. Other possible repairs include:

• Repair or replace the faulty knock sensor
• Repair or replace the wiring and connectors for the knock sensor circuit
• Verify the proper octane for the vehicle
• Cleaning out carbon deposits in the engine’s cylinders
• Replace the malfunctioned spark plugs
• Repair or replace the worn-out rod bearings

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If an engine knock can be heard, fix the source of the mechanical problem first then retest. Make sure the proper octane of fuel was used in the engine. Using lower octane fuel than what is specified can cause a ping or pre-detonation and lead to P0331.

• Unplug the knock sensor and check for water or corrosion in the connector.
• Ensure that 5 Volts are present at the KS connector.
• If resistance is out of specification, replace the knock sensor. If resistance is normal, plug KS back in and idle the engine.
• Verify the knock sensor wiring isn't routed next to ignition wires
• Unplug each sensor one at a time until the reference voltage returns. When it returns the last sensor, you plugged in is the shorted sensor. If no sensors are shorted, check the wiring harness for short to voltage on reference circuit.

Common Mistakes When Diagnosing the P0331 Code

It is always recommended to have a proper diagnosis of your vehicle by an experienced technician or diagnostician because usually people change the knock sensor at first place rather than checking it thoroughly and end up with the same error code as the actual reason of error was something else.