P0330 OBD-II: Knock Sensor 2 Circuit

OBD II Fault Code

• OBD II P0330

Fault Code Definition

• Knock Sensor #2 - Circuit Malfunction (Single Sensor or Bank 2)

What does this mean?

The knock sensor 'tells' the Powertrain Control Module that the engine is pinging. This is important because a pinging engine pollutes the air with excessive NOx gases. NOx causes acid rain as well as severe respiratory problems. This is one reason why there is much higher levels of asthma in large cities with high levels of vehicle air pollution.

Code P0330 Indicates there's a malfunction in the circuitry that controls and monitors the #2 knock sensor.

P0330 Symptoms

• Check Engine Light will illuminate
• Engine pings on accelration
• Engine may be running hotter than normal
• In rare cases, the engine may not exhibit noticeable symptoms

Common Problems That Trigger the P0330 Code

• Defective Knock Sensor
• Defective Knock Sensor Circuit or connections
• Defective EGR System
• Malfunctioning Cooling System
• Lean air/fuel ratio

Common Misdiagnosis

• Knock Sensor replaced when cause of code P0330 was a cooling system problem
• Knock Sensor replaced when cause of code P0330 was an EGR system malfunction

P0330 Diagnostic Theory for Shops and Technicians

When diagnosing a P0330 code, it is important to record the freeze frame information and then duplicate the code setting conditions with a test drive at the recorded freeze frame conditions. Carefully watch the serial data stream readings for each and any knock sensor. Are you able to verify that the knock sensor is sending a signal to the PCM? If so, look at the coolant temp readings, do they look normal? If not, deal with this ASAP, because an overheating engine will most certainly cause any engine to knock. If the engine temp is normal, check long term fuel trim, to ensure that the engine isn't running too lean, as this too can cause NOx formation. If the fuel and cooling system and verified engine temp, as measured with a lazer/infared pyrometer, is normal, then I often tap the engine block with a small hammer and watch the knock sensor and timing serial data to see how the sensor reacts to this type of physical test. If possible I will visually inspect the sensor and its wiring to see if there's evidence of chafing and/or corrosion. If you come to the conclusion that the sensor should be replaced, then I always replace the knock sensor harness as well because the harness commonly causes problems and most modern day knock sensors are buried underneath the intake manifold, so this bit of a preventative measure, replacing the harness, has saved me from several hours of frustration.