What and where is the Knock sensor?

[NottsLCR]

Had the car on VAGCOM tonight and it has thrown up 4 codes relating to the knock sensor. What is it and where is it?
I've read on google its purpose and the symptoms on Ross Tech just want a simple explanation of it and where it is.
The part seems fairly cheap if it needs replacing, I've been having problem with a loud ticking which is believed to be the cam chain tensioner but is this related?

Cheers

 

[DannyC87]

knock sensor detects engine knock, otherwise known as pre-detonation. This normally occurs when the timing is advanced too far for the modifications and petrol being used. Best bet is to log your CFs (timing correction factors) using VAGCOM to see if your knock sensors are giving realistic readings; your issue may be too much advance rather than a dodgey sensor.

 

[Slimy]

Yep, a knock sensor fault is usually an indication of a problem somewhere else. For example, when did you last change your spark plugs?

 

[NottsLCR]

Cheers guys, I'll try to log this weekend but I have never done any loggingbefore so i'll do some reading first - As its to do with timing could be the cam chain tensioner then? Spark Plugs are fairly new due to the recent engine flood

 

[Slimy]

I see from your signature that you have a hybrid fitted, do you have an appropriate map? I wonder whether the the hybrid could be messing up your fuelling and causing pre-detonation? Or is the ticking a recent thing?

 

[Pyro]

Cheers guys, I'll try to log this weekend but I have never done any loggingbefore so i'll do some reading first - As its to do with timing could be the cam chain tensioner then? Spark Plugs are fairly new due to the recent engine flood

dont think the tencionor will have an efect my friend mines been gone for a while now and i get nothing

 

[NottsLCR]

Hybrid hasnt been mapped to suit yet as afew days after fitting the FPR failed (not believed to be related) and flooded the engine with petrol.

I've tried to get a mapped twice but both times something has happend, first cracked DP then the engine flood. Pyro im booked in Thursday to get this checked out so hopefully this is the cause and can get it fixed so i'll let you know after your help if its sorted

 

[DannyC87]

as said.. cam chain tensioner shouldn't cause pre-det IMO.. the suspect causes would be fuelling and spark timing.

 

[Pyro]

would a faulty coilpack cause it ??

 

[DannyC87]

would a faulty coilpack cause it ??

That'd throw up the random misfire fault code 18### as well..

 

[MJ]

would a faulty coilpack cause it ??

just poor running and porformance issues

 

[NottsLCR]

No misfire codes just the following:
17733 - Cyl.1-Knock Contr. Limit Attained
17734 - Knock-Control: Cylinder 2: Regulation Limit Exceeded
16712/16717 - Knock Sensor 1/2 (G61): Signal too High

 

[DannyC87]

sounds like something is causing predet rather than a sensor issue to me. Both sensors are suggesting knock..

 

[NottsLCR]

Whats things would you check?

I cleared the codes so will see if there back tomorrow after my trip to work and back

 

[DannyC87]

Whats things would you check?

I cleared the codes so will see if there back tomorrow after my trip to work and back

Without a log of your CFs and fuelling I couldn't comment.

As you say, clear them and they may not come back. If I boot mine from cold (not that I would under normal circumstances) I get a load of knock errors..

 

[Pyro]

as said log your CF's i think its 20 and 03 change plugs what fuel do you run?

 

[NottsLCR]

Ok will check codes tomorrow and try logging.

I always use the Tesco 99RON now Momentum think its called......