Technical Description of OBD-II Trouble Code
Intermittent Knock Sensor Circuit (Bank 1)
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to OBD-II equipped vehicles such as Dodge, Ram, Ford, GMC, Chevrolet, VW, Toyota, etc. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
Whenever I have encountered the diagnosis of a stored code P0329, it has indicated that the powertrain control module (PCM) has detected an intermittent knock sensor signal for engine bank two. The term “knock sensor 1” can refer to a specific sensor in a multiple sensor configuration or the single sensor in a single sensor configuration. Bank 1 refers to the bank of the engine that contains the number one cylinder. To determine the configuration of the knock sensor system for the specific vehicle, consult a reliable source of vehicle information.
The knock sensor is typically threaded directly into the engine block and is a piezoelectric sensor. The location of the sensors in a multi-sensor system may vary among manufacturers, but most are located on the sides of the block between water jacket freeze plugs. Knock sensors that are on the sides of the engine block are often threaded directly into engine coolant passages. It is important to note that removing these sensors when the engine is warm and the engine cooling system is under pressure can result in severe burns from hot coolant. Therefore, before removing any knock sensor/s, allow the engine to cool and always dispose of coolant properly.
The knock sensor contains a piezoelectric sensing crystal, which produces a small amount of voltage when shaken or vibrated. Since the knock sensor control circuit is usually a one-wire ground circuit, the PCM recognizes the voltage generated by the vibration as engine noise or vibration. The severity of the vibration experienced by the piezoelectric crystal inside the knock sensor determines the level of voltage produced in the circuit.
If the PCM detects a level of knock sensor voltage that indicates spark detonation, it may retard ignition timing and no knock sensor control code will be stored. However, if the PCM detects a level of knock sensor voltage that indicates a more severe engine noise, such as a connecting rod contacting the inside of the engine block, it may discontinue fuel delivery and ignition spark to the affected cylinder, and a knock sensor code will be stored.
A small amount of voltage is always produced by the knock sensor when the engine is running because a slight amount of vibration is inevitable, regardless of how smoothly the engine runs. If the PCM detects an unexpected signal from knock sensor 1, such as battery voltage, complete battery ground, or pulsing voltage, a code P0329 will be stored, and a malfunction indicator lamp (MIL) may be illuminated.
Other knock sensor/circuit trouble codes related to this issue include P0324, P0325, P0326, P0327, P0328, P0330, P0331, P0332, P0333, and P0334.
Severity of the Code & Symptoms
A stored code P0329 could indicate severe internal engine failure. Therefore, it should be addressed with some degree of urgency.
Symptoms of this code may include:
Causes
Possible causes for this code to be set are:
Diagnostic and Repair Procedures
To diagnose a code P0329, you will need a diagnostic scanner, a digital volt/ohmmeter, and a reliable source of vehicle information. If the engine sounds like it is knocking or excessively noisy, address that issue before attempting to diagnose any knock sensor codes.
Refer to your vehicle information source for technical service bulletins (TSB) that correspond to the exhibited symptoms and stored codes in the specific vehicle. If the problem you are experiencing is a common one, the appropriate TSB may assist in a successful diagnosis. Follow the diagnostic steps outlined in the TSB to likely arrive at the correct solution.
I prefer to begin with a visual inspection of all system-related wiring harnesses and connectors. I am looking for burnt, corroded, or otherwise damaged wiring and connectors that may create an open or shorted circuit. Knock sensors are often located in the lower part of the engine block, making them susceptible to damage during the replacement of heavy parts such as starters and engine mounts. System connectors, wiring, and fragile knock sensors are frequently broken during repairs in the vicinity.
Connect the scanner to the vehicle’s diagnostic connector and retrieve all stored codes and freeze frame data. Write down this information for use in the diagnostic process. Clear the codes and test drive the vehicle to see if any codes are reset.
If the P0329 code is reset, start the engine and use the scanner to monitor knock sensor data. If the scanner indicates that the knock sensor voltage is not within the manufacturer’s specifications, use the DVOM to test live data at the knock sensor connector. If the signal at the connector is within specifications, suspect a wiring issue between the sensor and the PCM. If the voltage at the knock sensor connector is not within specifications, suspect a defective knock sensor.
Additional diagnostic notes:
