What does it mean when the knock sensor of the 7th generation Accord has no signal?
3 Answers
This indicates that the sensor is malfunctioning or the wiring is not properly connected. The function of the knock sensor is to transmit engine knock in the form of an electrical signal to the electronic control module, serving as a crucial basis for the control module to adjust ignition timing to prevent further knocking. Below is relevant information: Function: The knock sensor is installed in the middle of the engine block. For a four-cylinder engine, it is placed between cylinders 2 and 3, or one between cylinders 1 and 2 and another between cylinders 3 and 4, to measure engine vibration and adjust the ignition advance angle when engine knock occurs. Types: There are various types of knock sensors, with the earliest being the magnetostrictive knock sensor, which mainly consists of a magnetic core, permanent magnet, and induction coil. When the engine vibrates, the magnetic core shifts, altering the magnetic flux within the induction coil and generating an induced electromotive force. Other types include the piezoelectric ceramic type, where the ceramic inside generates a weak electrical signal when the engine vibrates, which is why the connecting wires of most knock sensors are shielded.
The seventh-generation Accord I just drove also had an alarm for no signal from the knock sensor. As an experienced driver with over a decade of experience, I know this is not a problem to be taken lightly. The knock sensor is a component installed on the engine to detect abnormal combustion. If it outputs no signal, it means it's no longer reporting data to the computer (ECU). This usually causes the ECU to mistakenly assume there's a risk of knocking, automatically retarding the ignition timing, resulting in noticeably weaker performance, sluggish acceleration, and increased fuel consumption. The possible causes are simple, such as the sensor itself aging, getting water damage, or the wiring connector becoming loose or corroded, leading to a disconnection. I used an OBD scanner to read the fault code, confirming it was a P0325 error, then checked the connector, cleaned it, and replaced the sensor, solving the issue for less than 200 yuan. Don’t delay fixing this—long-term neglect could lead to increased engine knocking, accelerated wear, or even part failures. Paying attention to the sensor’s condition during regular maintenance is very useful, especially for seventh-generation Accords, which often have such minor issues.
Car repair is my hobby. I've studied the issue of no signal from the knock sensor on the seventh-generation Accord. It's that small device that detects changes in engine combustion sounds. No signal means the sensor isn't sending any readings to the computer. Possible failure points include damaged internal components of the sensor, oxidized/broken circuit wires, or loose connectors - common issues in older vehicles. I'd first use an OBD scanner to check for trouble codes like P0325, then measure resistance with a multimeter: normal reading should be around a few kilo-ohms, infinite resistance means it's definitely broken. Replacing the sensor is simple - just align it properly and tighten, costing about a hundred yuan. When the ECU receives no signal, it conservatively retards ignition timing to protect the engine, but this leads to reduced power and higher fuel consumption. Prolonged operation can cause piston or valve damage. Keeping wiring harnesses dry and regularly cleaning engine dust can reduce risks.
