P0328 code: Knock Sensor 1 Circuit High (Bank 1)
P0328 means knock Sensor 1 Circuit High (Bank 1). The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0328 means
The knock sensor "listens" for the rattle of detonation (pinging) so the computer can pull ignition timing before it damages the engine. P0328 means the signal from knock sensor 1 on Bank 1 is reading HIGHER than the expected range — as opposed to P0327, which is the same circuit reading low. Common causes are a failing sensor, a wiring fault or short pulling the signal high, a loose or over-torqued sensor (mounting torque matters, since the sensor reads vibration through its body), or genuine excessive engine noise from something mechanical. With an untrustworthy knock signal the computer plays it safe and runs conservative ignition timing, which you may notice as mild sluggishness and slightly worse fuel economy — the engine is protected, just detuned.
P0328 symptoms
- Check-engine light, often with no obvious change
- Slightly sluggish acceleration
- Minor drop in fuel economy
- Pinging under load in some cases
What it costs to fix P0328
Typical range: $150–$600 · about ~0.5–3 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Knock sensor | $40–$200 | ~0.5–3 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
The sensor is cheap; labor varies wildly by engine. On many V-type engines the knock sensors sit in the valley under the intake manifold, so most of the bill is removing the intake to reach them. On engines with the sensor on the block's side, it's a quick job.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0328 for my exact vehicle →
How to fix P0328
Moderate — doable at home with common tools and patience
- Check freeze frame and knock-retard data
Note the RPM and load when P0328 set, then watch knock retard or knock count on live data where your scanner shows it. Heavy retard at a quiet, light-load idle suggests the computer is seeing a false signal from the circuit; retard only under hard acceleration, with audible pinging, points toward real detonation or mechanical noise.
- Inspect the Bank 1 sensor harness for shorts and breaks
Bank 1 is the side with cylinder 1, and on inline engines it's the only bank. Follow the knock sensor wire for insulation rubbed through against coil or injector feeds, a damaged shield, or terminals pushed back in the connector. A signal wire touching a powered circuit, or an open that lets the computer's bias voltage float on many systems, both read as circuit high.
- Measure the circuit with the sensor unplugged
Key on, sensor disconnected: compare the voltage on the harness signal pin with the value in the service manual — a reading at or near battery voltage means a short to power somewhere along the run. Then, with the computer unplugged too, check end-to-end continuity on each knock sensor wire to catch an open.
- Test the sensor and how it's mounted
Measure the sensor against your engine's spec; some read a defined resistance and others read open by design, so don't condemn one on an OL reading alone. Confirm it's bolted to a clean, bare-metal boss at the specified torque, with no washer, sealer, or paint under it unless the manual calls for one — a loose or overtightened sensor misreads vibration.
- Chase real engine noise if the circuit tests clean
When the wiring and a new sensor both check out and the code returns, the sensor may be hearing something genuine: valvetrain clatter, piston slap, a loose bracket bolted near it, or rod knock. Listen with a mechanic's stethoscope around the sensor boss — a real mechanical noise needs a shop diagnosis before it becomes engine damage.
DIY or shop? The electrical checks — harness inspection, a voltage reading on the signal pin, continuity tests — are home-mechanic work with a multimeter and a wiring diagram. Replacement is the variable: on many inline engines the Bank 1 sensor sits on the block beneath the intake runners and can be reached from below, while on V engines it may be under the intake manifold, which means gaskets and hours. Hand it to a shop if the manifold has to come off or if the evidence suggests genuine mechanical noise rather than a wiring fault.
Tools for the DIY steps: Digital multimeter · Wiring diagram · Scan tool with knock-retard data · Torque wrench · Mechanic's stethoscope · Socket set with extensions
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0328.
Start a case with P0328 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0328?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0328: common questions
What does 'circuit high' mean on P0328?
The voltage or signal level from the sensor is above the range the computer expects — the mirror image of P0327 (circuit low). It usually points to the sensor itself, a wiring short pulling the signal high, or a mounting problem, since knock sensors read vibration through their body and are sensitive to torque.
Can I drive with P0328?
That's more than a code can say on its own. The computer defaults to conservative ignition timing when it loses a trustworthy knock signal to protect the engine — so it may feel slightly less responsive and efficient. Address it sooner if you hear pinging under load.
Why is a cheap sensor sometimes an expensive repair?
On many V6 and V8 engines the knock sensors are mounted in the valley beneath the intake manifold, so the intake has to come off to reach them — that labor is most of the cost. On engines with an accessible block-mounted sensor, it's an inexpensive job.
Could P0328 mean my engine is actually knocking?
It's possible — a persistently high signal can reflect real mechanical noise the sensor is picking up, not just an electrical fault. If the code comes with audible rattling, ticking, or pinging, have the engine listened to before simply replacing the sensor.
Symptoms that trigger P0328
Drivers who get this code often notice one of these. Each has its own causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0328 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0328 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.