Knock sensor fault code
25 September 2011, 04:10 PM
#31
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Not that I know of. Car was pretty standard even down to exhaust when bought. I've not checked the ecu mind. But the CEL only started coming on in the last couple weeks. All I have done is put a catback system on which hasn't made much difference to be fair. Not mapped in but still has the original downpipe on.
I've been out, removed everything and cleaned under the knock sensor and refitted everything.
Warmed car up, reset ecu and it flashed a steady all clear. Great, I thought. Took her out and within half a mile light was back on. Then off and a nice straight came up. Give some beans upto 4th and she pulled brilliantly. Did it more over 10 miles and the CEL would come on periodically and the Scoob would hesitate with or without it on. Other times it would run fine.
I'm at a loss as it can't be the knock sensor if the cars acting the same after. Is it maf or lambda??
I've been out, removed everything and cleaned under the knock sensor and refitted everything.
Warmed car up, reset ecu and it flashed a steady all clear. Great, I thought. Took her out and within half a mile light was back on. Then off and a nice straight came up. Give some beans upto 4th and she pulled brilliantly. Did it more over 10 miles and the CEL would come on periodically and the Scoob would hesitate with or without it on. Other times it would run fine.
I'm at a loss as it can't be the knock sensor if the cars acting the same after. Is it maf or lambda??
25 September 2011, 04:25 PM
#32
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How are the terminals in the multiplug for the knock sensor? I would have suspected that if the MAF or lambda were an issue, the ECU would have a DTC memorized. Not to say it isn't the maf or lambda but i'd check the terminals for the knock sensor, make sure they're nice and tight, not corroded in anyway, and are making good contact with the knock sensor terminals
25 September 2011, 06:35 PM
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*******! I genuinely thought my problem was solved...
Right I took everything apart AGAIN. Decided to clean all the connectors and pressed the metal pins for a tight fit. Did another ecu reset and let the car warm up some more. Took it out for a spirited drive and she was wonderful. Boost bang on and everything was sweet. No hesitation and no CEL.
But when I got home and let her idle for a bit the frigging light came on again
Connected black plugs and you guessed it number 22 - knock sensor.
What have I done wrong? Everything was finethen on a cool down it came on again and has the hesitation back.
I turned the car over and unplugged the maf, it conked out pretty quick. Does this mean the maf is fine? Or is it my next port of call?
Right I took everything apart AGAIN. Decided to clean all the connectors and pressed the metal pins for a tight fit. Did another ecu reset and let the car warm up some more. Took it out for a spirited drive and she was wonderful. Boost bang on and everything was sweet. No hesitation and no CEL.
But when I got home and let her idle for a bit the frigging light came on again
Connected black plugs and you guessed it number 22 - knock sensor.
What have I done wrong? Everything was finethen on a cool down it came on again and has the hesitation back.
I turned the car over and unplugged the maf, it conked out pretty quick. Does this mean the maf is fine? Or is it my next port of call?
Last edited by chocolate_o_brian; 25 September 2011 at 06:41 PM.
25 September 2011, 06:48 PM
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*******! I genuinely thought my problem was solved...
Right I took everything apart AGAIN. Decided to clean all the connectors and pressed the metal pins for a tight fit. Did another ecu reset and let the car warm up some more. Took it out for a spirited drive and she was wonderful. Boost bang on and everything was sweet. No hesitation and no CEL.
But when I got home and let her idle for a bit the frigging light came on again
Connected black plugs and you guessed it number 22 - knock sensor.
What have I done wrong? Everything was finethen on a cool down it came on again and has the hesitation back.
I turned the car over and unplugged the maf, it conked out pretty quick. Does this mean the maf is fine? Or is it my next port of call?
Right I took everything apart AGAIN. Decided to clean all the connectors and pressed the metal pins for a tight fit. Did another ecu reset and let the car warm up some more. Took it out for a spirited drive and she was wonderful. Boost bang on and everything was sweet. No hesitation and no CEL.
But when I got home and let her idle for a bit the frigging light came on again
Connected black plugs and you guessed it number 22 - knock sensor.
What have I done wrong? Everything was finethen on a cool down it came on again and has the hesitation back.
I turned the car over and unplugged the maf, it conked out pretty quick. Does this mean the maf is fine? Or is it my next port of call?
Checked everything on and around engine for tightness/space/interference? If somethings rattling the knock sensor could pick it up and wrongly assume it's knock
Last edited by TH3_5T1G; 25 September 2011 at 06:50 PM.
25 September 2011, 06:54 PM
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Bugger! The MAF could still be working but just giving ECU incorrect signal voltage for actual amount of air flow. Usually when the MAF does cause the engine to run lean, you'll get knock. However, as said before, 'usually' ECU will pick this up and have DTC's stored.
Checked everything on and around engine for tightness/space/interference? If somethings rattling the knock sensor could pick it up and wrongly assume it's knock
Checked everything on and around engine for tightness/space/interference? If somethings rattling the knock sensor could pick it up and wrongly assume it's knock
I haven't really the spare cash for another maf and lambda unless someone could lend me known working ones to test out?
Dunno, had enough of her today.
25 September 2011, 06:59 PM
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Afaik everything is fine. Stuffs tight, checked wires for touching or being near to each other. Had the intercooler etc off 3 times today and I'm losing the will to live
I haven't really the spare cash for another maf and lambda unless someone could lend me known working ones to test out?
Dunno, had enough of her today.
I haven't really the spare cash for another maf and lambda unless someone could lend me known working ones to test out?
Dunno, had enough of her today.
You'll get there eventually
25 September 2011, 08:25 PM
#38
OK, Andy, back to my original comment: if you have changed the knock sensor, and it's STILL showing knock, why are you assuming the sensor is wrong? It would seem to be showing SOMETHING. Knock, maybe? That DOESN'T mean you'll HEAR it, just that you have det.
Also, you mention in your post, and have mentioned to me, that "boost is bang on". How do you KNOW that without a gauge? "It feels right" doesn't cut it mate. It's just daft to keep saying it, and may put people who know the cars off the trail. Don't assume......it makes an *** out of u and me
That idea of unplugging the MAF sensor when the engine is running is a myth. It does nothing.
You REALLY need to speak to, or take it to, someone who knows what he/she is doing. Preferably BEFORE you get any damage
If you can't afford it at present, then drive the Pug for a while.
Also, you mention in your post, and have mentioned to me, that "boost is bang on". How do you KNOW that without a gauge? "It feels right" doesn't cut it mate. It's just daft to keep saying it, and may put people who know the cars off the trail. Don't assume......it makes an *** out of u and me
That idea of unplugging the MAF sensor when the engine is running is a myth. It does nothing.
You REALLY need to speak to, or take it to, someone who knows what he/she is doing. Preferably BEFORE you get any damage
If you can't afford it at present, then drive the Pug for a while.
Last edited by alcazar; 25 September 2011 at 08:26 PM.
25 September 2011, 08:32 PM
#39
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OK, Andy, back to my original comment: if you have changed the knock sensor, and it's STILL showing knock, why are you assuming the sensor is wrong? It would seem to be showing SOMETHING. Knock, maybe? That DOESN'T mean you'll HEAR it, just that you have det.
Also, you mention in your post, and have mentioned to me, that "boost is bang on". How do you KNOW that without a gauge? "It feels right" doesn't cut it mate. It's just daft to keep saying it, and may put people who know the cars off the trail. Don't assume......it makes an *** out of u and me
That idea of unplugging the MAF sensor when the engine is running is a myth. It does nothing.
You REALLY need to speak to, or take it to, someone who knows what he/she is doing. Preferably BEFORE you get any damage
If you can't afford it at present, then drive the Pug for a while.
Also, you mention in your post, and have mentioned to me, that "boost is bang on". How do you KNOW that without a gauge? "It feels right" doesn't cut it mate. It's just daft to keep saying it, and may put people who know the cars off the trail. Don't assume......it makes an *** out of u and me
That idea of unplugging the MAF sensor when the engine is running is a myth. It does nothing.
You REALLY need to speak to, or take it to, someone who knows what he/she is doing. Preferably BEFORE you get any damage
If you can't afford it at present, then drive the Pug for a while.
Points taken Jeff
Obviously I can't tell if there is det, just go on what I know about these and my previous my99.
What's your recommendation Jeff? With regards who to listen to it? The place I used to use in Rotherham is in Cornwall now so out the question
25 September 2011, 09:58 PM
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I've asked in general about Sheffield Subaru Service as it's a more local place. Harvey was definitely in my thoughts though after what he's done for you Jeff.
Will call them tomorrow and see if I can pop into Sheffield after work one day.
Will call them tomorrow and see if I can pop into Sheffield after work one day.
26 September 2011, 05:31 PM
#42
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Bit of an update as this may be beneficial to others in the future...
Rang Richard Henry motorsport up at work this morning. Explained situation and Andy the gaffer (great name!!) said to pop through for a diagnostic check after work. Went through at about 3.30 and no issue there, seemed to boost fine and bo audible noises. But CEL came on on some roads as approaching. Least there would be a fresh reading for the diagnostics machine.
22 as per. Basically what Andy says the issue is, is simply an electrical gremlin on the knock sensor. No dodgy maf or actual knock, just a buggered wire. Apparently more common than you think. So scoob is booked in next Tuesday for a rewire of the knock sensor. Basically off the main loom, taped off securely and a new wire through the bulkhead straight into the ecu.
Very nice chaps and I'm fingers crossed this is the solution.
Will update next week.
Andy
Rang Richard Henry motorsport up at work this morning. Explained situation and Andy the gaffer (great name!!) said to pop through for a diagnostic check after work. Went through at about 3.30 and no issue there, seemed to boost fine and bo audible noises. But CEL came on on some roads as approaching. Least there would be a fresh reading for the diagnostics machine.
22 as per. Basically what Andy says the issue is, is simply an electrical gremlin on the knock sensor. No dodgy maf or actual knock, just a buggered wire. Apparently more common than you think. So scoob is booked in next Tuesday for a rewire of the knock sensor. Basically off the main loom, taped off securely and a new wire through the bulkhead straight into the ecu.
Very nice chaps and I'm fingers crossed this is the solution.
Will update next week.
Andy
04 October 2011, 01:13 PM
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As promised I took the Scoob to Richard Henry this morning. Went for a mooch with the mrs and little 'un whilst Andy did his magic.
Hour later and job done. Has chopped the knock sensor wire off at both the ecu and loom ends, and run a fresh insulated wire through a grommet in the bulkhead straight into the ecu. Reset the ecu and the fault code was gone.
Car drives spot on again now and didn't cost me a fortune either. Think I have my new Subaru specialists now
Well those and the Subaru place in Sheffield.
Hopefully this thread will help others with electrical niggles.
Hour later and job done. Has chopped the knock sensor wire off at both the ecu and loom ends, and run a fresh insulated wire through a grommet in the bulkhead straight into the ecu. Reset the ecu and the fault code was gone.
Car drives spot on again now and didn't cost me a fortune either. Think I have my new Subaru specialists now
Well those and the Subaru place in Sheffield.
Hopefully this thread will help others with electrical niggles.
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