Technical Description of OBD-II Trouble Code
The knock sensor 2 circuit on Bank 2 is experiencing a range/performance issue.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to vehicles equipped with OBD-II. While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
Knock sensors are used to detect engine pre-detonation, also known as engine knock or ping. The knock sensor (KS) is typically a two-wire sensor. It receives a 5-volt reference from the sensor and sends a signal back to the PCM (powertrain control module). The sensor signal wire informs the PCM when a knock occurs and the severity of the knock. The PCM will adjust the spark timing to prevent pre-detonation. Most PCMs can learn spark knock trends during normal engine operation.
If the PCM determines that the knock is abnormal or the noise level is unusually high, it may trigger the P0331 code. If the PCM detects severe knock that cannot be resolved by adjusting the spark timing, it may also set the P0331 code. It’s important to note that knock sensors cannot differentiate between knock caused by pre-detonation or other engine issues. Bank 2 refers to the side of the engine that does not contain cylinder #1.
Symptoms
Common symptoms of the P0331 DTC may include:
Causes
Possible causes of the P0331 code include:
Possible Solutions
If an engine knock is audible, it is important to address the underlying mechanical issue before retesting. Ensure that the engine has been fueled with the correct octane rating, as using lower octane fuel than specified can lead to pinging or pre-detonation and trigger the P0331 code.
Disconnect the knock sensor and inspect the connector for water or corrosion. If the knock sensor has a seal, check for any coolant from the engine block that may be affecting the sensor. Repair as necessary.
With the engine off and the ignition in the run position, verify that there is a 5-volt presence at the knock sensor connector. If there is, check the resistance between the knock sensor terminal and the engine ground, referring to the vehicle’s specifications. If the resistance is outside of the specified range, replace the knock sensor. If the resistance is normal, reconnect the knock sensor and let the engine idle. Use a scan tool to monitor the knock sensor value in the datastream. Does it indicate the presence of knock at idle? If so, replace the knock sensor. If the knock sensor does not show any knock at idle, tap on the engine block while observing the knock signal. If the signal does not correspond with the taps, replace the knock sensor. If it does, ensure that the knock sensor wiring is not routed near ignition wires. If there was no 5-volt presence at the knock sensor connector while unplugged with the key on and engine off, return to the PCM connector. Turn off the ignition and cut the knock sensor 5-volt reference wire in a location that can be easily repaired (or remove the wire from the PCM connector). With the key on and engine off, check for 5 volts on the PCM side of the cut wire. If 5 volts is not present, suspect a faulty PCM. If 5 volts is present, repair any short in the 5-volt reference circuit.
Since the reference circuit is shared, it is necessary to check all engine sensors that receive a 5-volt reference. Unplug each sensor one at a time until the reference voltage returns. The last sensor that was plugged in before the voltage returned is the likely shorted sensor. If none of the sensors are shorted, inspect the wiring harness for any short to voltage on the reference circuit.
