Diagnostic Trouble Code (DTC) Information ECM-304D

Condition 

Fig 1: Identifying Knock Sensor

Courtesy of VOLVO CARS CORPORATION

In certain operating conditions the engine control module (ECM) checks the signal from the rear knock sensor (KS). The diagnostic trouble code (DTC) is stored if the signal from the rear knock sensor (KS) is too low in these operating conditions.

The diagnostic trouble code (DTC) can be diagnosed when the engine is running.

Substitute Value 

• Safety retardation of ignition advance
• Reduced boost pressure.

Possible Source 

• Contact resistance in the knock sensor (KS) terminals
• Open-circuit in the signal cable
• Short-circuit between the knock sensor (KS) signal cables
• Damaged knock sensor (KS).

Fault symptom[s] 

• Poor performance.