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Knock Sensor Fault in holden commodore 2006

Mohammed Mohsin

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Does knock sensor fault causes effect like miss fire engine?

As before i was getting fault code for fuel injectors then my car mechanic did change ECM or all the electronics then the fault for fuel injectors went away but now new fault code for knock sensor appears, and by the way after changing ECM, car radio disolay and dome interior light as flashing just like hazard? Can anyone have idea about it how to solve this issues?
 
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Crowny

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Last time I had an injector fault code I ended up having the injector replaced which was a relatively cheap and easy fix. However when that happened the "Check Powertrain" warning came on and the car would miss a beat, so my issue might be different to yours.
 

Mohammed Mohsin

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Last time I had an injector fault code I ended up having the injector replaced which was a relatively cheap and easy fix. However when that happened the "Check Powertrain" warning came on and the car would miss a beat, so my issue might be different to yours.
This was the case with before i change anything
 

Jolls

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Hi Mohammed

The radio and dome light are controlled by the BCM so I am unsure how changing the ECM can affect them. Was it immediately after the ECM was changed? If so check with the Mechanic to see what else he may have touched. If not it is time to diagnose the BCM - check the fault codes etc.

In regards to the knock sensor you need to identify exactly what the code is and follow the diagnostics guide from the manual (you can download from a link on this site if you do a search).

From the manual:

The knock sensor (KS) signal is used by the ECM to provide optimum ignition timing while minimising engine knock or detonation. The ECM monitors the voltage of the left-hand (Bank 2) sensor during the 45 degrees after cylinder 2, 4, or 6 has fired and the voltage of the right-hand (Bank 1) sensor during the 45 degrees after cylinder 1, 3, or 5 has fired.
If knock occurs in any of the cylinders, the ignition will be retarded by three degrees for that particular cylinder. If the knocking then stops, the ignition will be restored to what it was before in steps of 0.75 degrees.
Should knocking continue in the same cylinder despite of the ignition being retarded, the ECM will retard the ignition an additional step of three degrees, and so on, up to a maximum of 12.75 degrees. The ignition will also be retarded at high ambient temperatures to counteract knocking tendencies provoked by high intake air temperatures.
Should either Bank 1 or Bank 2 sensor fail to work, or should an open circuit occur, the ignition timing will then be set at a default strategy that will retard the ignition much more than normal.

In short if the knocks sensor has failed you will be running a retarded engine. PErformace and fuel economy will be poor.


 

Mohammed Mohsin

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Hi Mohammed

The radio and dome light are controlled by the BCM so I am unsure how changing the ECM can affect them. Was it immediately after the ECM was changed? If so check with the Mechanic to see what else he may have touched. If not it is time to diagnose the BCM - check the fault codes etc.

In regards to the knock sensor you need to identify exactly what the code is and follow the diagnostics guide from the manual (you can download from a link on this site if you do a search).

From the manual:

The knock sensor (KS) signal is used by the ECM to provide optimum ignition timing while minimising engine knock or detonation. The ECM monitors the voltage of the left-hand (Bank 2) sensor during the 45 degrees after cylinder 2, 4, or 6 has fired and the voltage of the right-hand (Bank 1) sensor during the 45 degrees after cylinder 1, 3, or 5 has fired.
If knock occurs in any of the cylinders, the ignition will be retarded by three degrees for that particular cylinder. If the knocking then stops, the ignition will be restored to what it was before in steps of 0.75 degrees.
Should knocking continue in the same cylinder despite of the ignition being retarded, the ECM will retard the ignition an additional step of three degrees, and so on, up to a maximum of 12.75 degrees. The ignition will also be retarded at high ambient temperatures to counteract knocking tendencies provoked by high intake air temperatures.
Should either Bank 1 or Bank 2 sensor fail to work, or should an open circuit occur, the ignition timing will then be set at a default strategy that will retard the ignition much more than normal.

In short if the knocks sensor has failed you will be running a retarded engine. PErformace and fuel economy will be poor.


Thanks Jolls, i was not expecting such deep explaination, about BCM let me check with that, albut for knock Sensor i checked the ECM as refer to attached screenshot it shows (Blank 2) knock sensor
 

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Jolls

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Hi Mohammed

I recommend you download the service manual and have a look at the diagnostic proceedure. I have paraphrased the diagnostics blow - so I trust this gets you on the right track:

Inspect the appropriate knock sensor (KS) for the following fault condition.
• incorrect KS attaching bolt torque value,
• burrs, casting flash or foreign material between the knock sensor
and engine,
• hoses, brackets or engine wiring touching the KS, and
• damaged KS wiring harness.
• sensor wiring harness for conditions that may induce
electromagnetic interference.
Was any fault found and rectified? If No:
Test the appropriate KS signal circuit and low reference circuit for a
high resistance, open circuit, short to ground or short to voltage or
shorted together fault condition. If No:
Replace the faulty KS.

Seriously mate - download the manual and it will help you work through the problem in clear and easy to follow steps.

Cheers
Jolls
 
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