Technical Description of OBD-II Trouble Code
Above Knock Threshold in Cylinder 9
What is the meaning of P2344?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to many OBD-II vehicles (1996-newer). This includes vehicles from Mercedes-Benz, Ford, Sprinter, Nissan, and others. Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
If your vehicle has stored a code P2344, along with a malfunction indicator lamp (MIL), it indicates that the powertrain control module (PCM) has detected a signal from the knock sensor in cylinder #9 that is outside of the acceptable threshold.
The knock sensor is responsible for monitoring excessive vibration and noise in an individual cylinder or bank of cylinders. It is part of a low voltage circuit that uses a chemical reaction to detect engine knock through changes in engine noise and resulting vibration. Engine knock can be caused by issues with timing, detonation, or internal engine failure. The modern knock sensor, made with piezoelectric crystals, reacts to changes in engine noise by producing a slight increase in voltage. Since the knock sensor is part of a low voltage circuit, any changes in voltage are easily detected by the PCM.
If the PCM detects an unexpected level of voltage in the knock sensor circuit for cylinder nine, it will store a code P2344 and illuminate the MIL. Multiple failure cycles may be necessary for the MIL to illuminate.
What is the severity of this DTC?
When a P2344 code is stored, it is important to diagnose the cause as soon as possible. The symptoms that contribute to this code being stored can range from minimal to catastrophic.
What are some of the symptoms of the code?
Symptoms of a P2344 trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P2344 troubleshooting steps?
Ensure that the engine has the correct oil level and is in good working condition. Any actual engine noise, such as spark knock, must be resolved before diagnosing a P2344 code.
To accurately diagnose a code P2344, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
It may be helpful to search for technical service bulletins (TSB) that match the stored code, vehicle information (year, make, model, and engine), and exhibited symptoms. This information can often be found in your vehicle information source. If you find the appropriate TSB, it may provide a quick solution to your diagnosis.
After connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and relevant freeze frame data, write down the information in case the code is intermittent. Then, clear the codes and test drive the vehicle until one of two things happens: either the code is restored or the PCM enters readiness mode.
If the PCM enters readiness mode at this point, the code may be more difficult to diagnose because it is intermittent. The condition that caused the P2344 code to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, continue with the diagnosis.
You can obtain connector face views, connector pinout charts, component locator charts, wiring diagrams, and diagnostic flow charts specific to the code and vehicle in question from your source of vehicle information.
Conduct a visual inspection of the related wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged. Spark plug wires and boots should be replaced as part of scheduled maintenance. If the vehicle has exceeded the recommended maintenance interval for a tune-up, suspect faulty spark plug wires/boots as the cause of a stored P2344 code.
After disconnecting the PCM, use the DVOM to check for continuity in the knock sensor circuit. Take caution when removing the knock sensor, as it is typically threaded into the engine block and can result in contact with coolant or oil. Test for continuity through the sensor and back to the PCM connector.
