P0331 OBD-II: Knock Sensor 2 Circuit Range/Performance (Bank 2)
Diagnostic Trouble Code (DTC): P0331
P0331 code definition
A P0331 code is stored when the powertrain control module (PCM) determines that an engine pre-detonation (knock or ping) has an abnormally high noise level or that it is out of the ordinary in some other way.
What the P0331 code means
Knock sensor 2, on engine bank 2, is designed to detect engine knocks or pings. This two-wire sensor sends a signal to the PCM to inform it of any instances of knocks or pings and how severe they may be. This input on normal knocks and pings allows the PCM to predict engine pre-detonation and account for it to predict knock trends and slow spark timing as necessary. If a knock or ping is too loud or too far out of the ordinary, the P0331 code will be saved, and the Check Engine light or MIL (Malfunction Indicator Light) will be illuminated.
What causes the P0331 code?
There are a few different causes for a P0331 code to be stored, including:
- Using the incorrect fuel octane
- A damaged knock sensor connector
- An open circuit to the knock sensor
- A knock sensor circuit that’s shorted to ground or voltage
- A faulty knock sensor
- Moisture in the knock sensor’s connectors
- A faulty PCM (rare)
What are the symptoms of the P0331 code?
Noticeable symptoms when a vehicle has a stored P0331 code include:
- An illuminated Check Engine Light or MIL
- A pinging from the engine upon acceleration
- An audible knocking coming from the engine
How does a mechanic diagnose the P0331 code?
When a mechanic diagnoses the problem causing a P0331 code to be stored, they will first listen to the engine while it’s running to determine if there is a knock or if the problem is more likely an issue with the sensor. After listening to the engine and visually inspecting it, they’ll address the issue causing the knock, clear the code, and retest to ensure that the sensor is not malfunctioning and there aren’t any other problems.
If there is no audible knock or the code is stored again after fixing the knock, the mechanic will unplug the knock sensor to inspect for corrosion or moisture in the connector. They will then take the proper diagnostic steps to address any issues with the knock sensor and retest the code again.
How serious is the P0331 code?
A knocking engine is at risk of leaving you stranded on the side of the road. If you hear a deep 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 malfunctioning knock sensor, the PCM will not be able to adjust for engine knock, and further engine damage can occur.
What repairs can fix the P0331 code?
A P0331 code may be fixed by simply cleaning corrosion from the knock sensor’s connectors and ensuring that there is no moisture in the connectors. Other possible repairs include:
- Using the proper octane for the vehicle and/or using an octane booster
- Cleaning out carbon deposits in the engine’s cylinders
- Replacing the spark plugs
- Repairing or replacing the rod bearings
- Repairing or replacing the knock sensor
- Repairing or replacing the wiring and connectors for the knock sensor’s circuit
Additional comments for consideration regarding the P0331 code
In addition to other problems that may occur due to a persistent abnormal engine knock and/or a faulty knock sensor, failing to diagnose and clear a P0331 code will make it impossible to pass an OBD-II emissions test, as the MIL or Check Engine light will be illuminated until the problem is resolved.
Need help with a P0331 code?
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