EN

Severity: Low Code type: Generic (all makes)

P0328 Code: Knock Sensor 1 Circuit High Input (Bank 1)

Knock sensor 1's signal is too strong: a short to voltage, electrical noise or a genuinely noisy engine.

At a glance

Severity: 2/5 – Low2/5

Severity: Low

Meaning
Knock Sensor 1 Circuit High Input (Bank 1)
System
Ignition & Misfire · Powertrain
Safe to drive?
Yes, short term
Typical repair cost
$50–$2,500
DIY difficulty
Moderate

P0328 is set when the signal from knock sensor 1 (bank 1, or the only sensor) rises above the highest level the engine computer expects. That can be electrical: the signal wire touching a powered circuit, the two sensor wires shorted together, or interference picked up from ignition coils or injector wiring routed alongside it. On some designs an open circuit also reads high, because the computer's bias voltage floats up with nothing connected. It can also be mechanical: an overtightened sensor, a loose bracket or heat shield, or an engine that has developed a real rattle such as a slapping timing chain, excessive valve clearance or bearing noise. Because a genuinely noisy engine can set this code, don't dismiss it as just a sensor.

Can I keep driving? Usually fine to drive gently. Run the recommended octane, and if you can hear a new knocking or rattling noise from the engine itself, get it checked soon, since that noise may be mechanical wear rather than a sensor fault.

How to read P0328

How to read P0328P10233284
  1. P Powertrain
  2. 0 Generic (SAE)
  3. 3 Ignition / misfire
  4. 28 Specific fault

Symptoms

  • Check-engine light and reduced power while the computer retards timing
  • New rattle or knock from the engine, sometimes only when cold
  • Code that appeared after new coils, injectors or wiring were installed
  • Rough idle or misfire codes if interference also affects other signals
  • Worse fuel economy

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Real mechanical noise from the engine: timing chain slap, loose valve clearance, piston slap or bearing knock 22%
  2. Signal wire shorted to a voltage source or to the other sensor wire 20%
  3. Electrical interference from coil or injector wiring routed next to the knock sensor harness, or a damaged shield 17%
  4. Loose heat shield, bracket or accessory rattling near the sensor 14%
  5. Sensor overtightened or the wrong type fitted 13%
  6. Open circuit on systems where an open reads as high bias voltage 9%
  7. Engine computer knock input fault 5%

Diagnosis step by step

Diagnostic flow: P03281Listen to the engine before touchingthe sensor2Unplug the sensor and watch the code3Check for a short to voltage4Look for interference and routingproblems5Check torque and surroundings

  1. Listen to the engine before touching the sensor

    With the engine idling cold and warm, listen with a stethoscope around the timing cover, valve covers and block. A rattle at the front on a cold start suggests timing chain wear, often alongside cam correlation codes. Any deep knock from the bottom end needs attention before the sensor does.

    Tools: Screwdriver, Flashlight

  2. Unplug the sensor and watch the code

    With the sensor unplugged, clear codes and run the engine. If P0328 changes to a low or circuit code, the wiring to the computer is probably fine and the problem is the sensor or what it's hearing. If P0328 remains, look for a short to voltage in the harness.

    Tools: OBD-II scanner

  3. Check for a short to voltage

    Key on, sensor unplugged, measure DC voltage on each sensor wire at the harness. Compare with the spec. A value at or near battery voltage or 5 volts means the wire is touching a powered circuit, often where the knock harness is bundled with coil or injector wiring.

    Tools: Multimeter

  4. Look for interference and routing problems

    Check that the knock sensor harness still follows its original path and hasn't been re-bundled with coil wires after a repair. Look for a damaged shield or a missing ground on shielded cables, and for aftermarket wiring running alongside.

    Tools: Flashlight

  5. Check torque and surroundings

    Remove the sensor, confirm it's the correct part and reinstall at the exact torque. Tighten any loose heat shields, brackets or accessory mounts near it.

    Tools: Torque wrench

Where the parts are

Ignition: coils and spark plugs per cylinder – P03281234567
Ignition: coils and spark plugs per cylinder
  1. 1Ignition coil
  2. 2Spark plug
  3. 3Fuel injector
  4. 4Camshaft sensor
  5. 5Crankshaft sensor
  6. 6Engine computer (ECM)
  7. 7Intake manifold

Repair options & costs

RepairDIY?Estimated cost
Repair or reroute shorted or noisy harness No $100–$400
Replace knock sensor and set correct torque Yes $150–$450
Tighten or replace loose heat shield or bracket Yes $50–$200
Replace timing chain, guides and tensioner No $900–$2,500
Adjust valve clearance No $250–$700

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

Subaru

On Subaru's older EJ-series boxer engines, knock sensor codes including P0328 are a familiar issue. The sensor sits on top of the block under the intake manifold, and its short pigtail and connector are easy to damage. Check the connector and torque before assuming the engine is noisy.

Field data

Honda 4 Pilot, Accord Plug In Hybrid
Volkswagen 2 Jetta, Tiguan

Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.

Emissions / smog test impact

Will fail

With P0328 turning on the check-engine light, the car fails an OBD emissions test. If the cause turns out to be mechanical noise, fix that first, or the code will return right after it's cleared.

Frequently asked questions

Can a noisy engine really cause P0328?

Yes. The knock sensor can't tell detonation from other sharp noises in its frequency range. A worn timing chain, loose valve clearance or a bearing knock can push the signal over the limit. That's why listening to the engine is the first step.

The code appeared after I installed new coils. Is that related?

Possibly. If the coil harness was re-routed next to the knock sensor wires, or a cheaper coil puts out more interference, the knock circuit can pick up the noise. Restore the original routing and check the harness shield.

Is P0328 the same as the engine knocking?

Not necessarily. It means the signal is too high for the computer to trust, which could be real knock, other engine noise or an electrical fault. The computer protects the engine by retarding timing either way.

Should I just replace the sensor?

Only after checking wiring, routing and engine noise. A new sensor won't fix a short to voltage, interference or a mechanical rattle, and those are common causes of a high-input code.

Sources