P0325: Knock Sensor 1 Circuit (Bank 1 or Single Sensor)
Key takeaways
- P0325 means the engine computer sees a fault in the circuit of knock sensor 1, the sensor that listens for detonation on bank 1 or on the whole engine.
- It is usually safe to drive, but the computer pulls ignition timing as a precaution, so expect a little less power and fuel economy.
- Damaged wiring or a corroded connector is common, and on many V6 and V8 engines the sensor sits under the intake manifold, which is what makes the bill high.
- An accessible sensor typically costs $150 to $400 installed; a sensor under the intake runs about $400 to $900.
- Several Chrysler-family bulletins fix P0325 with an engine computer update, so ask for a bulletin check before buying a sensor.
What P0325 means
Your engine computer isn’t getting a usable signal from the sensor that listens for engine knock. Scanners call it “Knock Sensor 1 Circuit (Bank 1 or Single Sensor)”; newer tools may say “Knock/Combustion Vibration Sensor 1 Circuit.” A knock sensor is a small microphone-like sensor bolted to the engine block. When fuel detonates too early (knock or ping), it produces a vibration signal, and the computer pulls ignition timing back to protect the pistons. If the signal is missing, out of range, or the circuit reads open or shorted, the computer sets P0325. Sensor 1 is bank 1, the side with cylinder 1, or the only knock sensor on engines that have one.
Is it safe to drive?
Yes, in most cases, and gently. Without a trustworthy knock signal the computer runs a conservative, retarded ignition timing, so the engine is protected but a little slower and thirstier. Use the octane your owner’s manual specifies, and avoid towing or long full-throttle climbs until it’s fixed.
The symptom that changes the answer: audible pinging or knocking when you accelerate, or a flashing check engine light. Pinging with a dead knock sensor means the engine may be knocking with nothing correcting it; ease off and get it checked soon. See our guide on whether you can drive with the check engine light on.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Damaged, chafed or rodent-chewed wiring, or a corroded connector | Inspect the harness and plug; check continuity and resistance back to the computer | $100–$250 |
| Engine software needing an update | A bulletin covers your make, model and year | $100–$200, or free under warranty |
| Failed knock sensor, easy to reach (most four-cylinders) | Sensor resistance or signal out of spec with good wiring | $150–$400 |
| Failed knock sensor under the intake manifold (many V6 and V8 engines) | Same tests, done at the connector; the sensor itself needs the intake removed | $400–$900 |
| Sensor loose or not torqued to spec after earlier work | Check the mounting bolt; a loose sensor reads weak | Covered by diagnosis, or $100–$250 |
What to check first
- Read the other codes. P0325 with P0330 (knock sensor 2, bank 2) points to shared wiring, a shared ground or software, not two failed sensors.
- Inspect the connector and harness. Oil, coolant leaks from the intake and rodents all damage knock sensor wiring. Find the problem at the harness and it may be a $100–$250 job.
- Ask for a bulletin check. The pattern is Chrysler-family software: engine computer reflashes on the 2025 Ram 1500, 2024 Jeep Grand Wagoneer and 2022 Ram ProMaster list P0325, and there is a separate P0325 bulletin for the 2020–2021 Jeep Wrangler. Ford has one for 2016–2017 Explorer 3.5L EcoBoost engines built on or before Sept. 30, 2016, and GM has one on the 2023 Escalade for reduced knock sensor detection.
- Test the sensor at the connector before anyone pulls the intake. If the sensor is buried, ask whether replacing both sensors and the harness while it’s open makes sense.
- Clear it and drive after a wiring repair or software update; a circuit fault usually resets the code within a drive or two.
15 complaints filed with NHTSA mention P0325, and the Chevrolet Cruze accounts for 4 of them. Those are owner reports, not confirmed causes.
What it costs
The cheap outcome is a wiring or connector repair at $100–$250, or a software update. The common outcome on a four-cylinder is a new knock sensor at $150–$400. The expensive outcome is a knock sensor under the intake manifold on a V6 or V8 at about $400–$900, almost all of it labor. Paying for an hour of diagnosis first saves money, because testing at the connector tells you whether the intake needs to come off at all.
Related codes
P0325 often shows up with P0330, the bank 2 knock sensor circuit code, or with its own range and voltage codes P0326, P0327 and P0328. If a misfire code like P0300 appears too, sort the misfire out first. For a refresher on what a steady light means, see check engine light on.
What owners report to NHTSA
15 complaints filed with NHTSA mention P0325, 11 of them since 2015, across 11 different models. The component owners most often filed it under: engine.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| CHEVROLET CRUZE | 4 | 2014, 2017, 2018 |
Manufacturer service bulletins that name P0325
11 technical service bulletins and manufacturer communications filed with NHTSA mention P0325, from 5 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- RAM 1500 (2025), bulletin 11010256: "Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): **P…
- JEEP GRAND WAGONEER (2024), bulletin 11011903: "Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): **P…
- CADILLAC ESCALADE (2023), bulletin 10231896: This technical bulletin provides repair information to correct a customer concern of Possible Audible Knock Due to Reduced Knock Sensor Detection Capability DTC P0325, P0330, P0326, P0331, P06B6 or P06B7 May be Set in Hi…
- RAM PROMASTER (2022), bulletin 10225249: Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further inves…
- JEEP WRANGLER (2020, 2021), bulletin 10222950: MIL Lamp On, DTC P0325 - Knock Sensor 1 Circuit
- FORD EXPLORER (2016, 2017), bulletin 10153933: Some 2016-2017 Explorer/Police Interceptor Utility vehicles equipped with a 3.5L EcoBoost engine built on or before 30-Sep-2016 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (D…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Can I drive with P0325?
Usually, yes. The computer can't hear knock, so it retards ignition timing to stay safe, and you lose a little power and mileage. Use the fuel grade your owner's manual calls for, avoid heavy towing and full-throttle runs, and get it checked if you hear pinging under load.
Why is replacing a knock sensor so expensive on some cars?
The part itself is not the expensive bit. On many V6 and V8 engines the knock sensors bolt to the block in the valley under the intake manifold, so the intake has to come off, which means hours of labor and new gaskets. On most four-cylinder engines the sensor is on the side of the block and much cheaper to reach.
Can bad gas cause P0325?
Not usually. Low-octane fuel causes real knock, which the sensor should report without a circuit code. P0325 is about the sensor's circuit or signal, so the wiring, connector, sensor or software is the likely cause.
Should I replace both knock sensors?
If both are under the intake manifold, many shops recommend it, because the labor to reach them is the same and the second one is often just as old. If only one is accessible, replace the one the tests point to.