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OBD-II Code · Sensors

P0327

Knock Sensor 1 Low Input

Severity

medium

Worth booking. It costs fuel, emissions or comfort until it is fixed.

Can you drive it

Only if running normally

A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.

Indicative cost (USD)

$150–$500

Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.

Knock sensor voltage low.

How a shop works this

Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.

  1. Note every code that is set, not just this one.

    Codes that appear together usually narrow the cause faster than any one of them read alone.

  2. Read the freeze frame — the conditions the fault was recorded under.

    Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.

  3. Confirm the fault is current rather than history.

    Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.

  4. Then work the likely-causes list in the order shown.

    That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.

If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.

Common symptoms

  • Check engine light

Likely causes

  • Failed sensorMost common
  • Wiring short to ground
Read the full diagnostic procedureP0327 is knock sensor 1 circuit low - the signal voltage or DC bias has fallen below the lower threshold, typically meaning the sensor is shorted to…

P0327 is knock sensor 1 circuit low - the signal voltage or DC bias has fallen below the lower threshold, typically meaning the sensor is shorted to ground, the harness is shorted, or the sensor itself has failed internally.

Cheapest-first

  1. unplug the knock sensor and measure resistance across its terminals.
  2. Piezo sensors should read about 4 to 5 megohms; resonant sensors about 90 to 110 kohm.
  3. A reading near 0 ohms means the sensor is internally shorted.
  4. With the connector unplugged and key on, the signal wire at the harness side should sit at a bias voltage (often around 2.5 V) provided by the PCM; if it stays near 0 V, the harness is shorted to ground.
  5. On any GM LS truck, before you touch the sensor, pull the intake manifold and inspect the knock sensor harness pigtails for green corrosion - this is the actual fault about 90% of the time on these platforms.
  6. Caveat: this is the single most misdiagnosed knock sensor code in the industry.
  7. Condemning the sensor before verifying the under-intake harness on GM trucks wastes a $400-700 intake R&R job.
Vehicle-specific patterns1999-2007 GM Silverado/Sierra/Tahoe/Yukon/Suburban/Avalanche 4.8/5.3/6.0 LS is THE epidemic platform for P0327 - the foam mat over the lifter valley…
  • 1999-2007GM Silverado/Sierra/Tahoe/Yukon/Suburban/Avalanche 4.8/5.3/6.0 LS is THE epidemic platform for P0327 - the foam mat over the lifter valley wicks moisture and corrodes the knock sensor pigtails and the connector at the rear of the engine harness. GM TSB 02-06-04-037 covers the AC Delco wiring harness 12601822 replacement.
  • 2003-2008Honda Accord/Element K24 sets P0327 from internal sensor failure (Honda part 30530-RAA-A01).
  • 2005-2010VW Jetta/Passat 2.0T (BPY) sets P0327 from coolant intrusion into the knock sensor connector.
  • 2006-2011Hyundai Sonata 2.4L Theta II has a TSB for shorted knock sensor wiring.

Estimated repair$80 to $700 (the $700 reflects a full GM LS intake removal plus harness 12601822 plus two knock sensors plus knock sensor foam pad).

Look up another code

P0327 — frequently asked

What does a P0327 code mean?

Knock sensor voltage low.

What causes a P0327 code?

Common causes: Failed sensor; Wiring short to ground.

What are the symptoms of a P0327 code?

Typical symptoms: Check engine light.

Is it safe to drive with a P0327 code?

Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $150-$500.

How do I diagnose a P0327 code?

Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.

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