P0329Generic code

P0329 Code: Knock Sensor 1 Circuit Input Intermittent (Bank 1 or Single Sensor)

The P0329 code means the signal from knock sensor 1 (bank 1) cuts out or jumps intermittently. The engine keeps running, but with the ignition timing retarded and less power. You can drive, but get it repaired, because uncontrolled knock can damage the engine.

Severity
Medium
Can I keep driving?
Yes, no immediate risk
Estimated cost
$40 to $450
Difficulty
Medium
System
Ignition and Misfires
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0329 code means

Without its signal, the computer retards the ignition timing for safety. The engine runs, but with less power and higher fuel use. The P0329 code is stored when the knock sensor signal comes and goes.

The knock sensor is a piezoelectric microphone bolted to the engine block. It generates a small alternating voltage from vibrations. Many computers apply a bias voltage to it (often 2.5 V) and watch that the signal stays around that value. Intermittent dropouts are usually caused by the connector or the wire, which sit under the manifold and suffer heat and oil.

The knock sensor page on this site shows how to test it step by step. Remember that the code tells you where the computer saw the fault, not necessarily which part is bad.

P0329 code symptoms

  • Check engine light on.
  • Loss of power and sluggish response.
  • Higher fuel use.
  • Audible pinging when you accelerate under load, if the sensor is not detecting.
  • In many cases you notice nothing else.

Likely causes of the P0329 code

  1. Damaged sensor connector or wire. It sits under the manifold, exposed to heat and oil.
  2. Failed sensor. The piezoelectric element cracks.
  3. Wrong tightening torque. A loose or over-tightened sensor changes its sensitivity.
  4. Open circuit from a loose connector.
  5. Computer. Uncommon.

How to diagnose the P0329 code step by step

  1. Read the knock retard in live data. It should be close to zero at idle.
  2. Inspect the connector and the wire. They are often under the intake manifold.
  3. Measure the sensor resistance according to the manual (some should read a specific high value and others infinity).
  4. Tap the block gently near the sensor with the engine idling. Timing retard should appear, or a signal on the oscilloscope.
  5. Check the bias voltage if the system uses one (often 2.5 V with the connector plugged in).
  6. Verify the tightening torque of the sensor against the manufacturer specification.

How to fix the P0329 code

  • Repair the connector or the wire.
  • Replace the sensor and tighten it to the specified torque, with no washers or sealant.
  • If there is real mechanical noise, repair it first.
  • Clear the codes and verify on a road test.

Technical reference data

  • Piezoelectric sensor with 1 or 2 wires.
  • Typical tightening torque: 15 to 25 N·m (about 11 to 18 lb-ft).
  • Common bias voltage: about 2.5 V.
  • These values are for orientation only. Check the manufacturer data for your engine.

Brand-specific notes

P0329 on GM

On GM V6 and V8 engines the knock sensors are under the intake manifold. Their wiring harness deteriorates with heat, and it is common to replace the harness and the sensors at the same time.

P0329 on Nissan

On Nissan V6 and V8 engines the knock sensors are under the intake manifold. Their wiring harness deteriorates with heat, and it is common to replace the harness and the sensors at the same time.

P0329 on Toyota

On Toyota V6 and V8 engines the knock sensors are under the intake manifold. Their wiring harness deteriorates with heat, and it is common to replace the harness and the sensors at the same time.

P0329 on Subaru

On Subaru the sensor usually fails because of poor tightening after another repair.

Frequently asked questions about P0329

Can I drive with a P0329 code?
Yes, with less power. Repair it without rushing, but do repair it: uncontrolled knock can damage the engine.
Does the sensor have to be replaced?
Only if the tests confirm it. The connector and the wire fail just as often, so test them before you blame the sensor behind the P0329 code.
What do bank and letter mean?
Bank 1 is the side with cylinder 1 and bank 2 is the opposite side (only on V engines). The letter A or B tells apart sensors of the same type. On the camshafts, A is usually intake and B is exhaust.
How much does it cost to fix P0329?
About $40 to $450, depending on how hard the sensor is to reach.
What does the P0329 code mean?
It is a generic OBD2 code that means the signal from knock sensor 1 cuts out or jumps intermittently.
Will a P0329 code clear itself?
The light can go out if the connection holds for several drive cycles, but an intermittent fault in the connector or wire will usually come back until it is repaired.

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