Diagnostic trouble code (DTC) information

Condition

Fig 1: Identifying Knock Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

Diagnostic trouble code (DTC) ECM-3420 is stored if the engine speed (RPM) is over 3000 RPM, the engine coolant temperature (ECT) is above 40 °C (104 °F) and the signal from the rear knock sensor (KS) is too high or too low.

Substitute Value

ignition retarded for safety reasons
reduced boost pressure

Possible Source

Signal too high:

short-circuit to supply voltage in the signal cable
worn engine

Signal too low:

open-circuit in signal cable
contact resistance in terminals
defective knock sensor (KS)
short-circuit between knock sensor (KS) signal cables

Fault symptom[s]

none