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P0327 Severity
Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.
For a proper diagnosis, RepairPal Certified shops have the equipment, tools, and expertise.
Moderate severity codes might not threaten the vehicle's safety or functionality immediately, but you should still get it diagnosed within a reasonable time frame to keep your car running well.
The knock sensor tells the engine control module (PCM) that the engine has an excessive vibration resulting from an incorrect fuel and air mixture. If the PCM does not receive a signal from the knock sensor, it will set code P0327. The check engine light may or may not be illuminated.
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OBD-II Code P0327 is defined as a Knock Sensor #1 - Circuit Low Input (Single Sensor or Bank 1)
The purpose of the knock sensor is to alert the PowerTrain Control Module or PCM that the engine is pinging or knocking. This is important because a pinging or knocking engine pollutes the air with poisonous Nitrogen Oxide gases that cause acid rain and promote respiratory diseases such as asthma.
Code P0327 indicates that the readings from the #1 Knock Sensor circuit are too low, is outside of its operational window and malfunctioning.
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The PowerTrain Control Module or PCM controls the degree of ignition system spark advance in order to achieve maximum power and fuel economy. When the knock sensor signals the PowerTrain Control Module or PCM that the engine is pinging or knocking, the first thing the PCM does is change the amount of timing advance by retarding it in controlled increments, until the knock sensor stops signaling the PCM that the engine is pinging.
P0327 Diagnostic Theory for Shops and Technicians
When the engine has advanced the timing an excessive amount and the knock signal still hasn't signaled that the engine is pinging, this is an irrational condition. The PCM knows that the signal from the #1 knock sensor circuit is lower than its normal operational window, is malfunctioning and/or there is an extraordinary engine condition such as a cold running engine and cooling system malfunction. Capture and document the freeze frame data so you have an idea of what operational conditions were present when the PCM triggered the P0327 code. Then do a visual inspection of the engine and cooling system, coolant level/condition and oil level/condition to verify that code P0327 wasn't caused by a failure of a mechanical system. Then start the engine and rev it a few times to see that it operates normally, making sure there isn't a severe mechanical condition such that, driving the vehicle could cause further damage. Test drive the vehicle with a data streaming scanner and pay close attention to the #1 Knock Sensor PID and the PID for timing advance. How is the knock sensor #1 circuit operating? Is it not sending signals when the engine is pinging? If so, find out why. Sometimes I bring the car back to the service bay and tap the engine with a small hammer and watch the knock sensor PID as well as the PID for timing advance.