Ignition & misfire · Powertrain · generic (SAE-defined)
P0325: Knock Sensor 1 Circuit (Bank 1 or Single Sensor)
P0325 means the engine computer detected a problem in the circuit for knock sensor 1, the sensor on bank 1 or the only knock sensor on the engine.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0325 sets
A knock sensor is a microphone-like device bolted to the engine block that produces a signal when it detects vibration from detonation. The powertrain control module (PCM) checks that the circuit is intact and that the sensor produces a plausible signal. P0325 sets when the circuit is open, shorted, or the signal is outside expected limits. Test conditions are manufacturer-specific.
Common causes of P0325
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Damaged or corroded knock sensor wiring or connector
- Failed knock sensor
- Harness damage from heat or prior repairs near the intake
- Knock sensor not torqued correctly to the block
- Coolant or oil intrusion in the connector
- Rarely, a PCM fault
P0325 symptoms
- Check engine light on
- Reduced power or sluggish acceleration
- Lower fuel economy
- Pinging or knocking under load in some cases
- Often no noticeable drivability change
How P0325 is diagnosed
- Record freeze frame data and check for other knock sensor codes.
- Inspect the knock sensor harness and connector for damage or corrosion.
- Measure sensor circuit resistance or voltage per service information.
- Check the sensor mounting torque, since an improperly tightened sensor reads incorrectly.
- Tap near the sensor with the engine idling and watch for a response on a scan tool or oscilloscope.
- Replace the sensor only after wiring and mounting are verified.
Typical fixes for P0325
- Repair the knock sensor wiring or connector
- Replace the knock sensor
- Replace a damaged knock sensor harness
- Correct the sensor mounting torque
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.
Manufacturer notes
On some V6 and V8 engines, knock sensors and their harness sit under the intake manifold, and harness damage there is a commonly reported cause.
Related codes & warning lights
P0325 FAQ
What does code P0325 mean?
P0325 means the engine computer detected a problem in the circuit for knock sensor 1, the sensor on bank 1 or the only knock sensor on the engine. The standard definition is "Knock Sensor 1 Circuit (Bank 1 or Single Sensor)."
Can I drive with a P0325 code?
Usually yes, but cautiously. Without a working knock sensor, the computer often retards ignition timing for safety, reducing power and mileage; avoid heavy loads and use the recommended fuel grade until it is repaired.
Can a bad knock sensor damage the engine?
Usually the computer protects the engine by retarding timing when the sensor fails, so damage is unlikely in normal driving. However, if real knock occurs and goes undetected, it can harm pistons over time.
Why are knock sensors hard to reach on some engines?
On many V engines the sensors sit in the valley under the intake manifold, so the manifold must be removed to access them.
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.