Car Knock Sensor
The Knock Sensor detects engine knock and sends a voltage signal to the ECM. The ECM uses the Knock Sensor signal to control timing. Engine knock occurs within a specific frequency range. The knock sensor, located in the engine block, cylinder head, or intake manifold is tuned to detect that frequency.
The knock sensor senses when fuel is burning unevenly and causing “knocking” or irregular vibrations in the engine. It consists of an electric coil that is wound around two ceramic rods with a magnet in the center. The vibration of the engine causes the rods to vibrate. This disturbs the coil’s magnetic field and alters the current passing through the coil. This disturbance returns to the computer as a signal pattern that the computer analyzes. The computer then determines whether the vibrations are characteristic of engine knocking.
There are special sensor testing machines, but 99% of the time if the code come up with a fault it will be faulty, fit a new one.
Usually one would use a scan tool to watch knock signal while tapping on the engine with a metal object to see if it picks it up
SYMPTOM
P0325-KNOCK SENSOR #1 CIRCUIT
WHEN MONITORED
With the ignition ON and the engine running.
SET CONDITION
The Knock Sensor circuit voltage falls below a minimum value at idle or deceleration. The minimum value is from a look-up table internal to the PCM and is based on engine rpm. DTC also sets if sensor output goes above 5.0 volts. One Trip Fault.
POSSIBLE CAUSES
- Intermittent condition
- Knock sensor signal circuit shorted to voltage
- Knock sensor signal circuit shorted to ground
- Knock sensor signal circuit open
- Knock sensor signal circuit shorted to knock sensor return circuit
- Knock sensor return circuit open
- Knock sensor
mark (mhpautos)
Read the guide below on using a meter, it will help
https://www.2carpros.com/articles/how-to-use-a-voltmeter
See the attachments below for troubleshooting
Images (Click to enlarge)
Mar 25, 2019 at 12:14 PM
(Merged)
