Diagnostic trouble code (DTC) information

Condition 

Fig 1: Identifying Knock Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

Diagnostic trouble code (DTC) ECM-3400 is stored if the engine control module (ECM) registers that the signal from the knock sensor (KS) is higher than 3.75 V or below 1.25 V for a couple of seconds.

Substitute Value 

• knock control is disabled
• ignition retarded for safety reasons.

Possible Source 

Signal too high: 

• short-circuit to supply voltage in the signal cable
• open-circuit in signal cable
• loose connections in connector
• defective knock sensor (KS).

Signal too low: 

• short-circuit to ground in the signal cable
• defective knock sensor (KS).

Fault symptom[s] 

Poor performance due to retarded ignition.