Engine codes
P0325: knock sensor 1 circuit (bank 1)
A knock sensor is a small microphone bolted to the engine block that hears the sharp ping of detonation. P0325 means the computer has lost a usable signal from sensor 1, so it can no longer listen for knock on that bank.
P0325: can I drive, and what will the labor cost?
Estimated labor, replace an accessible knock sensor
$55 to $132
| Labor time (estimate) | 0.5 to 1.2 h |
| Rate used | $110/h |
| Technician wage, United States (average) | $27.13/h |
| Moderate: fix within weeks Drivable; most engines retard ignition timing as a precaution, so expect less power and mileage, and avoid heavy loads. | |
Labor only: parts and the diagnostic fee are not included. Hours are our estimate for a typical car; book times vary by model. Wage: BLS, May 2025.
P0325 is the generic OBD-II code for "knock sensor 1 circuit, bank 1 or single sensor". The knock sensor is a piezoelectric element that turns vibrations of the engine block into a voltage. When fuel ignites too early or explodes instead of burning smoothly, the block rings at a characteristic frequency, and the computer retards ignition timing to stop it. P0325 means the circuit is open, shorted, or the signal is outside the range the computer expects. Without the sensor, most engines play safe and run with less spark advance, so you feel less power and get lower mileage, particularly under load. The most frequent causes are wiring and connectors, often in a harness under the intake manifold that heat and oil degrade, and the sensor itself. A loose mounting bolt and rodent damage are less frequent. It is drivable, but avoid heavy loads and towing until it is fixed.
Is this repair still under the emission warranty?
Catalytic converter
Likely covered: ask a dealer
| Federal emission warranty, 8 years or 80,000 miles | within |
Age counts from delivery to the first buyer; whichever limit comes first ends the warranty. Your warranty booklet lists the covered parts and prevails.
Codes, rules and labor data checked by Radif Partners · Editorial policy · Method and sources
P0325 at a glance
| Code | P0325 |
| Standard description | Knock Sensor 1 Circuit (Bank 1 or Single Sensor) |
| System | Ignition and misfire |
| Severity | Moderate: fix within weeks |
| Common symptoms | sluggish acceleration, lower mileage, pinging under load |
Why the location matters so much
Some knock sensors are bolted to the side of the block and take well under an hour to replace. On many V6 and V8 engines, though, they sit in the valley between the cylinder banks, under the intake manifold. Replacing them then means removing the intake, with new gaskets, which is why the labor table shows a second range of 2.5 and 5 hours. Since the sensors and their harness are reached at the same time, shops often replace both sensors and the pigtail together.
Torque is part of the repair
A knock sensor's output depends on how firmly it is clamped to the block. Too loose and it hears too little; too tight and it can crack. The service information gives a torque, often low, and following it is part of a correct repair. Thread sealant should not be used unless the maker specifies it.
Knock codes and misfires
A knock sensor circuit code does not mean the engine is knocking; it means the computer cannot tell. If you hear pinging under acceleration, use the octane the maker recommends and avoid load until the sensor works again. A misfire, which shakes the engine, can trigger a knock signal on some engines, so if P0300 is stored with it, look at the misfire first. Timing codes such as P0016 are a separate issue.
Likely causes of P0325, in order
| Cause | How often |
|---|---|
| Damaged wiring or connector, often under the intake manifold | most frequent |
| Failed knock sensor | most frequent |
| Sensor mounting bolt loose or corroded | less frequent |
| Rodent damage to the harness | less frequent |
P0325 repairs and labor time
| Repair | Labor (estimate) | At $110/h |
|---|---|---|
| Replace an accessible knock sensor | 0.5 to 1.2 h | $55 to $132 |
| Replace a knock sensor under the intake manifold | 2.5 to 5 h | $275 to $550 |
| Repair the knock sensor harness | 0.5 to 2 h | $55 to $220 |