What this code means
P0325 may indicate that the PCM is not seeing the knock sensor signal as expected.
What the vehicle may do
- The vehicle may drive normally.
- The vehicle may have reduced performance or timing-control changes.
- The code can sometimes appear only after driving conditions allow the monitor to run.
Possible fault areas
- Possible knock sensor installation concern.
- Possible knock sensor circuit concern.
- Possible damaged knock sensor.
- Possible engine, fuel, cooling, PCV, oil maintenance, spark plug, fuel injector, or PCM-related concern.
Diagnostic path
Opening and code direction
On this 2015 to 2025 F-150 with the 2.7 EcoBoost, P0325 is a knock sensor code. In plain language, the PCM may not be seeing the knock sensor signal the way it expects. The truck may drive normally, or it may have timing-control changes, reduced performance, or a code that only resets after some driving. Broadly, this can involve knock sensor installation, the sensor circuit, the sensor itself, or other engine and operating conditions that can create knock-related concerns. Start with the basic system checks, then confirm the target knock sensor code is actually present. If other codes are present, check what they mean first, because a different knock-control path can change where you start. Before going deeper, make sure the knock sensor is correctly installed.
Check the knock sensor circuits for an open
With the ignition off, disconnect the KS11 connector, the KS21 connector, and the PCM connector. For KS11, check the circuit between C1047 Pin 2 and C1233E Pin 12, and between C1047 Pin 5 and C1233E Pin 33. For KS21, check between C1047 Pin 3 and C1233E Pin 10, and between C1047 Pin 6 and C1233E Pin 31. The resistance needs to be less than 5 ohms. If all of those readings are less than 5 ohms, keep going. If not, repair the open circuit, clear the PCM DTCs, and repeat the self-test.
Check for shorts to ground and shorts to voltage
Next, check the knock sensor circuits for a short to ground. On KS11, the checks are at C1047 Pin 2 and C1047 Pin 5. On KS21, the checks are at C1047 Pin 3 and C1047 Pin 6. The resistance needs to be greater than 10K ohms. If it is not greater than 10K ohms, repair the short circuit, clear the PCM DTCs, and repeat the self-test. If that passes, turn the ignition on and check the same KS11 and KS21 circuit points for a short to voltage. If any voltage is present, repair the short circuit, clear the PCM DTCs, and repeat the self-test. If no voltage is present, move on to the intermittent check.
Check for an intermittent open, then check bias voltage
With the ignition off, watch resistance while you wiggle, shake, and bend small sections of the harness from the sensor back toward the PCM. Use the same circuit pairs from the open-circuit check: KS11 between C1047 Pin 2 and C1233E Pin 12, and between C1047 Pin 5 and C1233E Pin 33; KS21 between C1047 Pin 3 and C1233E Pin 10, and between C1047 Pin 6 and C1233E Pin 31. The resistance still needs to stay less than 5 ohms. If it does not, repair the open circuit, clear the PCM DTCs, and repeat the self-test. If the harness passes, reconnect the PCM, turn the ignition on, and check bias voltage. KS11 is checked between C1047 Pin 2 and C1047 Pin 5. KS21 is checked between C1047 Pin 3 and C1047 Pin 6. The expected range is between 2.2 - 2.7 V. If the voltage is in that range, this path supports installing a new knock sensor, then clearing the PCM DTCs and repeating the self-test. If the voltage is not in that range, continue to the PCM operation check.
Knock-count branch when the code check points there
There is also a knock-count branch in this same diagnostic path. Use it when the initial code check points you there, rather than mixing it into the P0325 circuit checks. Start the engine, access the PCM, and monitor the cylinder knock-count PIDs for all six cylinders. If the majority of knock counts are on one cylinder, concentrate on the ignition coil and fuel injection components for that suspect cylinder, repair or install a new component as necessary, clear the PCM DTCs, and repeat the self-test. If the counts are not concentrated on one cylinder, continue into the fuel and road-test portion. Before chasing sensor logic on an audible engine knock, treat the noise as a possible base-engine concern.
Monitor knock rate under load
For the next branch, drain and clean the fuel system, then refill it with the correct grade fuel. Start the engine, capture the conditions from the stored fault data, clear the PCM DTCs, reset keep alive memory, and bring the engine to normal operating temperature before the road test. Monitor the cylinder knock-count PIDs again, then road test with mid to high throttle applications so the engine sees high continuous load without a downshift for 5 to 10 miles. If the knock counts do not increase, the system is operating correctly at this time. If the counts increase, move to the audible-knock decision.
Decide whether the knock is audible
After that road test, turn the ignition off and decide whether an audible knock was present during the drive. If there was an audible knock, check for base-engine concerns, repair as necessary, clear the PCM DTCs, and repeat the self-test. If there was no audible knock, look for issues such as harness routing, alterations, incorrect shielding, fuel injector noise, or electrical interference from nearby systems. Repair any concern you find. If no other concern is present, this branch supports installing a new knock sensor, then clearing the PCM DTCs and repeating the self-test.
Check PCM connector condition and operation
For the PCM operation check, disconnect all PCM connectors and inspect them closely for pushed-out pins and corrosion. Then reconnect all PCM connectors and make sure they seat correctly. After that, verify whether the concern is still present. If it is still present, this path supports installing a new Powertrain Control Module. If the concern is gone, the system is operating correctly at this time, and the issue may have been a loose or corroded connector.
Verification and takeaway
Keep verification separate from the testing. After a wiring repair, knock sensor replacement, PCM replacement, or any repair made in the knock-count branch, clear the PCM DTCs and repeat the self-test. The takeaway on P0325 is simple: confirm the code, make sure the sensor is installed correctly, prove the knock sensor circuits in order, and let the measured results decide whether you stay with wiring, move to the sensor, or continue to PCM checks. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0325 is best approached by confirming the code, checking sensor installation, proving the knock sensor circuits, and then following the measured results instead of guessing.
For more guided automotive diagnostics, visit STEP Diagnostics.
