Ignition & misfire · Powertrain · generic (SAE-defined)
P0327: Knock Sensor 1 Circuit Low (Bank 1 or Single Sensor)
P0327 means the signal from knock sensor 1 (bank 1 or single sensor) is lower than the engine computer expects, often from an open circuit, a ground fault, or a loose sensor.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0327 sets
The powertrain control module (PCM) monitors the knock sensor signal for a minimum level of background engine vibration or a bias voltage. If the signal stays below that expected level under certain conditions, P0327 sets. The thresholds vary by manufacturer and engine.
Common causes of P0327
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Open or shorted-to-ground knock sensor wiring
- Loose knock sensor or incorrect mounting torque
- Failed knock sensor
- Corroded connector or terminal
- Damaged harness under the intake manifold
P0327 symptoms
- Check engine light on
- Slight loss of power
- Reduced fuel economy
- Often no noticeable symptoms
How P0327 is diagnosed
- Confirm the code and note conditions in freeze frame data.
- Inspect wiring and connector at knock sensor 1.
- Check sensor mounting torque against specification.
- Measure resistance or bias voltage at the sensor connector per service information.
- Check signal wiring for continuity to the PCM and for shorts to ground.
Typical fixes for P0327
- Repair open or grounded wiring
- Tighten the sensor to the specified torque
- Replace the knock sensor
- Replace the knock sensor harness
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0327 FAQ
What does code P0327 mean?
P0327 means the signal from knock sensor 1 (bank 1 or single sensor) is lower than the engine computer expects, often from an open circuit, a ground fault, or a loose sensor. The standard definition is "Knock Sensor 1 Circuit Low (Bank 1 or Single Sensor)."
Can I drive with a P0327 code?
Generally yes. The engine computer usually retards timing to prevent detonation, so expect somewhat reduced power and fuel economy until the fault is fixed.
Why would a loose knock sensor set P0327?
A knock sensor needs firm contact with the engine block to pick up vibration. If it is loose or overtightened, the signal can fall below the expected level.
Can a knock sensor be tested at home?
Basic checks such as resistance and visual inspection are possible with a multimeter, but confirming signal output usually requires an oscilloscope or scan tool data.
Keep researching
Engine guides by brand (known issues, specs)
More ignition & misfire codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.