P0327 -What Does It Mean? (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon)

The 1999-2006 V8 equipped Chevrolet Silverado (Suburban, Tahoe) GMC Sierra (Yukon, Yukon XL) comes equipped with 2 knock sensors.

When knock sensor 1 malfunctions, the fuel injection computer will set a trouble code P0327: Knock Sensor No. 1 Circuit Problem.

In this tutorial, I'll explain what this trouble code means. I'll also talk about some of the tests you can perform to find its cause.

NOTE: The knock sensor is also known as the detonation sensor.

You can find this tutorial in Spanish here: Código P0327 ¿Qué Significa? (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon) (at: autotecnico-online.com).

APPLIES TO: This tutorial, on the P0327 OBD II trouble code, applies to the following vehicles:

Chevrolet:

• Silverado (1500, 2500):
  • 4.8L, 5.3L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Silverado (2500):
  • 6.0L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Suburban (1500):
  • 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Suburban (2500):
  • 6.0L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Tahoe:
  • 4.8L, 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006

GMC:

• Sierra (1500, 2500):
  • 4.8L, 5.3L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Sierra (2500):
  • 6.0L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Yukon:
  • 4.8L, 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Yukon XL (1500):
  • 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Yukon XL (2500):
  • 6.0L: 2000, 2001, 2002, 2003, 2004, 2005, 2006

RELATED TROUBLE CODES:

• P0332 -What Does It Mean? (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon).

What Does Trouble Code P0327 Mean?

The 4.8L, 5.3L, and 6.0L V8 engines comes equipped with 2 knock sensors. The front knock sensor is called knock sensor 1 and the rear one is called knock sensor 2.

Both knock sensor 1 and knock sensor 2 are located on the engine and underneath the intake manifold.

A trouble code P0327: Knock Sensor No. 1 Circuit Problem lets you know that the front knock sensor (located nearest to the front of engine) is not functioning properly.

To be a bit more specific, this code tells you that the PCM is receiving an AC voltage signal from the knock sensor that is too low or too high.

Common Symptoms Of A P0327 Trouble Code

Depending on the severity of the problem, you'll see one or more of the following symptoms:

• Engine knock (ping) when accelerating the vehicle.
• Lack of power when accelerating under load.
• The vehicle will not pass the emissions test.

What Does The Knock Sensor Do?

The fuel injection computer is constantly trying to advance ignition timing as far as possible.

If the ignition timing is advanced too far, the engine will knock (also known as engine ping, spark knock, or engine detonation).

If the engine is experiencing engine knock, the knock sensor will produce an AC voltage signal that's sent to the fuel injection computer.

The amount of AC voltage that the knock sensor produces is proportional to the amount and strength of the engine knock.

Once your Chevrolet Silverado or GMC Sierra's fuel injection computer receives the knock sensor's signal, it'll then retard ignition timing to reduce/eliminate the engine knock.

What Causes A P0327 Trouble Code?

A bad front knock sensor will cause a P0327 trouble code to set and the check engine light will illuminate on your Chevrolet Silverado (Suburban, Tahoe) GMC Sierra (Yukon, Yukon XL).

The 4.8L, 5.3L, and 6.0L engines are notorious for corrosion, due to excessive moisture accumulating under the intake manifold, to disable the knock sensors.

Other things that can cause a P0327 trouble code are:

• Internal engine mechanical problem causing the engine to knock.
• The knock sensor has been replaced and it's loose or over-torqued.
• Excessive lean air/fuel mixture causing spark knock in the engine cylinders.
• Vacuum leak from bad intake manifold gaskets causing an extreme lean air/fuel mixture.
• Damaged or corroded knock sensor connector.

How To Diagnose And Repair A P0327 Trouble Code

You can troubleshoot and repair a trouble code P0327 by testing the front knock sensor. If it's bad, replacing it will solve the trouble code.

Before replacing the knock sensor (since this bad boy is located underneath the intake manifold), I recommend the following:

• Testing the internal resistance of the knock sensor (specification: 9.3 to 107 K Ohms).
• Checking for intake manifold leaks.
• Making sure that an engine mechanical problem is not causing engine knock (ping).
• Checking fuel pressure.

Testing knock sensor 1 is not difficult at all. I've written a tutorial on how to do it and you can find it here:

• How To Test The Knock Sensors (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon).

If you do replace the knock sensor, replace both the front and rear knock sensors and their wiring harness.

Where To Buy The Knock Sensor And Save

When replacing knock sensor 1, it's recommended that you replace the rear knock sensor and their wiring harness too.

Due to the amount of labor required to replace the knock sensors (you've got to remove the intake manifold), I want to also recommend that you avoid buying cheap brand-X knock-off knock sensors.

The following links will help you comparison shop for these items of known brand names (AC-Delco, Dorman, Standard Motor Products):

NOTE: The AC-Delco brand is the original equipment part for the Chevrolet Silverado (Suburban, Tahoe) and GMC Sierra (Yukon, Yukon XL).

More Silverado, Sierra, Suburban, Tahoe, And Yukon Tutorials

You can find a complete list of V8 Chevrolet Silverado (Suburban, Tahoe) GMC Sierra (Yukon, Yukon XL) tutorials in this index:

• GM 4.8L, 5.3L, 6.0L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• Resistance Specifications Of The TAC Electronic Throttle Body.
• How To Test The GM Accelerator Pedal Position (APP) Sensor 2.
• How To Test The MAF Sensor (GM 4.8L, 5.3L, 6.0L, 8.1L).
• Blown Head Gasket Test (GM 4.8L, 5.3L, 6.0L).