OBD-II trouble code
P0326: Knock Sensor 1 Circuit Range/Performance (Bank 1 or Single Sensor)
SAE J2012: Knock Sensor 1 Circuit Range/Performance (Bank 1 or Single Sensor). The signal is present and outside the expected window. Test the mounting torque, the connector, and the sensor output. The module may retard timing while it does not trust the signal.
Quick facts
- System
- Powertrain
- Category
- Knock & Other
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $400 – $600
- DIY difficulty
- Intermediate DIY
Browse every code in P0300–P0394, or start from the full code library.
What does P0326 mean?
A knock sensor is essentially a microphone bolted to the engine block that listens for the high-frequency vibration of detonation (knock). When the PCM hears knock, it retards ignition timing to protect the engine from damage. P0326 is the 'range/performance' fault for knock sensor 1 (bank 1 or the single sensor on inline engines): the sensor is producing output, but the signal is outside the expected window — too low in amplitude, erratic, or not correlating with engine speed and load the way a healthy sensor's should. That's different from P0325 (general circuit), P0327 (circuit low), and P0328 (circuit high); here the sensor is alive but its performance is off.
Because the complaint is a believable-but-wrong signal, the causes lean toward the sensor and its mounting rather than a dead circuit. A sensor that has drifted, and a mounting bolt that is not at the published torque, are both on the list. Knock sensors are torque-sensitive: a loose or over-tight sensor can read incorrectly. Neither is a published majority. A corroded or loose connector, wiring that has picked up resistance or noise, and contamination at the sensor can all distort the signal. Engine mechanical noise from an unrelated problem can sometimes be misread as an out-of-range knock signal too. Diagnosis confirms the sensor's output against known-good behavior, checks the connector and wiring, and verifies the sensor is mounted and torqued correctly before replacement.
The driver may see a check engine light and less power or economy if the module retards timing because it does not trust the signal. Without a trusted knock signal, real detonation can go uncorrected under load or on fuel below the specified octane. Plan the repair.
Common causes
- Improperly torqued knock sensor mounting bolt (loose or over-tight) — costs nothing to correct and mimics a failed sensor
- Corroded or loose sensor connector
- Contamination at the sensor or connector
- Wiring resistance or electrical noise distorting the signal
- Aging knock sensor that has drifted out of range
- Engine mechanical noise misread as an out-of-range knock signal
- Damaged sensor after nearby service
Symptoms
- Check engine light with P0326 stored
- Slightly reduced power if the PCM retards timing as a precaution
- Minor drop in fuel economy
- Usually little or no noticeable drivability change
- Possible pinging under load if real knock isn't being controlled
- Sometimes paired with other knock-sensor codes
Diagnostic steps
- 1.Check what your scan tool can actually show you. Most tools report knock retard or knock counts rather than the sensor's raw output, which is a useful clue but is not the sensor's signal; seeing the signal itself takes a lab scope. Start with what is available and read it against engine speed and load for a plausible response.
- 2.Inspect the sensor connector and wiring for corrosion, looseness, and resistance.
- 3.Verify the knock sensor is mounted directly to clean metal and torqued to specification — torque strongly affects its reading.
- 4.Check for engine mechanical noise that could be misinterpreted as an out-of-range knock signal. Anything done with the engine running means a hot engine and a cooling fan that can start unprompted with the key on — keep hands, sleeves and probe leads clear of it and of the belt drive.
- 5.Tap the block near the sensor with a small wrench while reading the sensor's two pins on AC millivolts, connector unplugged, and watch for a pulse. A dead element produces nothing. Note two limits: many handheld meters sample too slowly to catch the pulse, so a flat reading on a cheap meter is inconclusive rather than a condemnation, and a resistance check exonerates nothing here — a piezo element fails by losing output, not by changing resistance.
- 6.Replace the knock sensor if mounting, wiring, and connector are correct but the signal stays out of range.
Repair cost
$400 – $600
Parts plus labor. RepairPal's national average for a knock sensor replacement is about $417–$589. This span rounds that to $400–$600. Torque is the published figure for this sensor, and correcting it is not a parts bill. Access that requires the intake is still inside a quote from the service-information labor time, which can move the job relative to the national average.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with knock sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.