P0328🔧 Knock sensor / ignition timingDrive with caution, fix soon

P0328: Knock Sensor 1 Circuit High Input (Meaning, Causes, Fixes)

Reviewed 2026-10-22 · Based on 2 cited source(s)

What P0328 means

A knock sensor is a small sensor bolted to the engine block that listens for engine knock (pinging or pre-detonation). When it reports knock, the engine computer (PCM) retards the ignition timing to protect the engine. OBD-Codes.com describes P0328 as a generic OBD-II code that refers to a high output voltage from the bank 1 knock sensor circuit, and says in many cases that means above 4.5 volts, though the exact value depends on the make and model. RepairPal defines it as Knock Sensor #1 Circuit High Input (Single Sensor or Bank 1) and says the readings are too high and outside the sensor's operating window. RepairPal's technician notes add that the computer can treat it as an irrational condition when it has already retarded the timing a lot and the sensor still reports knock, which may mean the sensor circuit is faulty or the engine really has a serious problem such as overheating or internal damage. The sources lean differently: OBD-Codes.com says the problem is most likely the sensor itself or its wiring once real knock and fuel octane are ruled out, while RepairPal puts more weight on engine-side causes and warns that replacing the sensor when the real cause was the cooling or EGR system is a common misdiagnosis. RepairPal's short summary also says the code sets when the computer receives no signal from the knock sensor, which doesn't match its own "circuit high" definition, so go by the definition and your vehicle's service information. P0327 is the matching low-input code for the same sensor.

Severity: can I keep driving?

Drive with caution, fix soon

Get it checked soon, but it's usually not an emergency. RepairPal rates P0328 Moderate, meaning it may not threaten safety right away but should be diagnosed within a reasonable time. RepairPal says a knock sensor reading this high can also point to a real engine problem such as overheating or internal damage, and ongoing pinging (knock) can damage an engine. If you hear knocking or pinging, the temperature gauge reads hotter than normal, or the engine loses power, ease off hard acceleration and get it looked at promptly.

Common symptoms

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

  1. Failed knock sensor (OBD-Codes.com, RepairPal)
  2. Knock sensor wiring or connector problems, such as a damaged connector, an open circuit, or a short to ground or to voltage (OBD-Codes.com, RepairPal)
  3. Loose knock sensor or electrical interference in the circuit (OBD-Codes.com)
  4. Real engine knock from incorrect fuel octane, low fuel pressure or a lean air/fuel mixture (OBD-Codes.com lists octane and fuel pressure; RepairPal lists a lean mixture)
  5. EGR system or cooling system problems (RepairPal)
  6. Mechanical engine problem (OBD-Codes.com; RepairPal mentions overheating or internal engine damage)
  7. Faulty PCM, less common (OBD-Codes.com)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

  1. Read all stored codes and note any others, especially cooling, EGR, lean or misfire codes, since they can explain real knock.
  2. Listen for knocking or pinging. If you hear it, OBD-Codes.com says to fix that mechanical cause first and then retest.
  3. Make sure you're using the fuel octane your owner's manual calls for; some engines require premium (OBD-Codes.com).
  4. Check coolant level and condition and engine oil level, as RepairPal suggests, before assuming the sensor is bad.
  5. Inspect the wiring and connectors from the knock sensor back to the engine computer for damage or corrosion (OBD-Codes.com).

Typical fixes

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

  • Testing the sensor and circuit needs a digital multimeter and the manufacturer's resistance and voltage specs (OBD-Codes.com)
  • Watching the knock sensor and timing advance readings while driving needs a scan tool with live data (RepairPal)
  • The engine is overheating, or you suspect internal engine damage
  • The code comes back after replacing the knock sensor; RepairPal warns that the real cause is sometimes the cooling or EGR system

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0328 serious?

RepairPal rates it Moderate. It often comes from the sensor or its wiring, but it can also go along with real engine knock or overheating, which can damage an engine. If you hear knocking or the engine runs hot, get it checked promptly.

Does P0328 always mean a bad knock sensor?

No. OBD-Codes.com says the sensor or its wiring is the most likely cause once real knock and fuel octane are ruled out, but RepairPal lists EGR, cooling system and lean mixture problems too, and says replacing the knock sensor when one of those was the real cause is a common misdiagnosis.

What's the difference between P0328 and P0327?

Both are for knock sensor 1 (bank 1 or a single sensor). P0328 means the signal is too high, while P0327 means it is too low.

How much does it cost to fix P0328?

Neither source gives a repair cost. It can range from a wiring repair or the right fuel to a new knock sensor or fixing an engine problem, so get a diagnosis and a written estimate first.

Sources

  1. OBD-Codes.com: P0328 Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor)
  2. RepairPal: P0328 Knock Sensor 1 Circuit High (rated Moderate)

Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.