P0327 OBD-II: Knock Sensor 1 Circuit Low

OBD II Fault Code

• OBD II P0327

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.

P0327 Symptoms

• Check Engine Light will illuminate
• Engine pings on accelration
• Engine may be running hotter or colder than normal
• In rare cases, the engine may not exhibit noticeable symptoms

Common Problems That Trigger the P0327 Code

• Defective Knock Sensor
• Defective Knock Sensor Circuit or connections
• Defective EGR System
• Malfunctioning Cooling System
• Rich air/fuel ratio

Common Misdiagnosis

• Knock Sensor replaced when cause of code P0327 was a cooling system problem
• Knock Sensor replaced when cause of code P0327 was an EGR system malfunction

Want to learn more?

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.