Knocking is a phenomenon characterized by undesirable vibration and noise and can cause engine damage. The knock sensor (KS) is attached to the cylinder block and senses engine knocking. A knocking vibration from the cylinder block is applied as pressure to the piezoelectric element. The knock sensor (KS) detects vibration upon increase and decrease in engine RPM and generates a voltage based on this vibration. The ECM controls the ignition timing based on the amplitude and frequency of the knock sensor signal. For example, if engine knocking occurs, the ignition timing is retarded to suppress it.
If there is little change in knock sensor’s signal, the ECM judged as a fault and DTC is set.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Signal at current segment is compared to previouse one | ● Poor connection ● Open or short in knock sensor circuit ● Defective knock sensor ● Defective ECM |
Enable Conditions | ● Time after start > 2sec ● Engine speed ≥2500rpm ● Load value ≥30% ● Duration = 200 segments | |
Threshold value | ● Amount of change IVp(t)-Vp(t-1)I < 0.06V | |
Diagnostic Time | ● Continuous | |
MIL ON condition | ● No MIL ON |
