What Does It Mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles (Dodge, Ram, Ford, GMC, Chevrolet, VW, Toyota, etc.). Although generic, specific repair steps may vary by make/model.
A stored P0324 code means the Powertrain Control Module (PCM) has detected a malfunction in the knock sensor control system.
The knock sensor control system typically consists of the knock sensor connector, wiring, and PCM. The knock sensor is a piezoelectric sensor usually screwed directly into the engine block. Sensor location varies by manufacturer, but most are found either on the sides of the block (between cylinder head coolant jacket freeze plugs) or under the intake manifold. Use caution when removing knock sensors located on the sides of the engine block, as they are often threaded directly into engine coolant passages.
Removing these sensors when the engine is hot and the cooling system is pressurized could result in burns from hot coolant. Before removing the knock sensor, allow the engine to cool sufficiently and drain coolant into a suitable container for legal disposal.
The key component of the knock sensor is a piezoelectric sensing crystal. When shaken or vibrated, the piezoelectric crystal produces a small voltage. Since the knock sensor control circuit is normally a single-wire ground circuit, the voltage generated by incidental vibration is recognized by the PCM as engine knock or ping. The voltage level produced depends on the severity of vibration encountered by the piezoelectric crystal inside the knock sensor.
Knock sensor control systems typically feature one knock sensor per engine bank, though some manufacturers use up to one knock sensor per cylinder. Consult a reliable vehicle information source for the knock sensor control system configuration of the specific vehicle.
If the PCM detects a knock sensor voltage level indicating spark knock; it may retard ignition timing to prevent engine damage and no knock sensor control code may be stored (unless very severe). If the PCM detects a knock sensor voltage level indicating more serious engine noise (like a connecting rod contacting the inside of the engine block), it may interrupt fuel delivery and ignition spark to the affected cylinder and a knock sensor code will be stored.
There’s almost always a very small voltage produced by the knock sensor when the engine is running. This is because however smooth the engine, slight vibration is inevitable. If the PCM detects an unexpected signal from the knock sensor, such as battery voltage, full battery ground, or pulsing voltage, a P0324 code will be stored and the MIL may illuminate.
Related knock sensor/circuit malfunction codes include P0325, P0326, P0327, P0328, P0329, P0330, P0331, P0332, P0333 and P0334.
Code Severity and Symptoms
A stored P0324 code could indicate serious internal engine failure. For this reason, it should be addressed with some urgency.
Symptoms of this code may include:
Decreased engine performance
Acceleration hesitation
Loud noises from engine area
Reduced fuel efficiency
Causes
Possible causes for this code being set include:
Faulty knock sensor
Internal engine malfunction
Engine misfire(s)
Contaminated or low-quality fuel
Defective knock sensor control wiring and/or connectors
Faulty PCM or PCM programming error
Diagnostic and Repair Procedures
A diagnostic scanner, digital volt/ohmmeter, and reliable vehicle information source will be needed to diagnose a P0324 code.
If the engine is knocking or excessively noisy in any way, correct this before attempting diagnosis for any knock sensor code.
Consult your vehicle information source for Technical Service Bulletins (TSBs) matching the symptom(s) displayed and code(s) stored in the vehicle in question. If the issue you’re experiencing is common; the correct TSB may aid successful diagnosis. Follow the diagnostic steps contained therein and you’ll likely reach a successful diagnosis.
Begin with a visual inspection of all wiring harnesses and connectors related to the system. Look for scorched, corroded, or otherwise broken wires and connectors that could create an open circuit and repair them. Some automakers place the knock sensor in the lower portion of the engine block. This can make it susceptible to damage during replacement of heavy components (like starters and motor mounts). System connectors, wiring, and fragile knock sensors are frequently broken when repairs are performed nearby. If no discrepancies are noted, proceed to the next step.
Connect the scanner to the vehicle’s diagnostic connector and retrieve all stored codes and freeze frame data. Record this information for use in the subsequent diagnostic process. Clear the codes and test drive the vehicle to see if the code resets.
If the code resets, start the engine and use the scanner to observe knock sensor data. If the scanner indicates knock sensor voltage isn’t within manufacturer specifications, use the DVOM to test live data at the knock sensor connector. If the signal at the connector meets specifications, suspect a wiring problem between the sensor and PCM. If voltage at the knock sensor connector doesn’t meet specifications, suspect a faulty knock sensor.
Additional diagnostic notes:
Knock sensor controller codes are typically limited to wiring, connectors, and controllers
Be cautious of knock sensors threaded into engine coolant passages