Knock sensor fault code
 

I've owned my current Scoob (MY99 UK wagon) for about two weeks and noticed that the "check engine" light has popped up twice. Once randomly not long after setting off on a journey and then again tonight at 10pm when I finished work. The engine was obviously stone cold and I took it easy coming home. Was on maybe a minute so thought best to connect the black connectors and check for fault codes.

This is a video of the fault code flicked up.

http://i64.photobucket.com/albums/h1...h_P1000449.jpg

So it seems the trouble is the knock sensor. Now forgive me for asking a stupid question but when this code crops up, does it mean I have knock or just the sensor is buggered/needs replaced? The engine sounds fine but it would explain a slight groggy feel the car has when cold in second around 2000rpm.

Can someone shed any light on this? I am hoping it is simply a case of sourcing and fitting a replacement sensor with an ECU reset afterwards.

Thanks,

Andy :thumb:

Somewhat annoyingly, there do seem to be a few cases where a faulty MAF sensor can cause the code 22 error. I don't know why this should happen but trustworthy, reliable people have reported it. Therefore, the fact that you are getting 22 adds to the suspicion. Although the first thing you should do in these circumstances is to check or replace the knock sensor.
You *can* check the knock sensor with a multimeter. Set it to resistance mode and see what you get across its two pins. The correct number should be 555Kohm +/- 5% or so. There should also be a direct connection (i.e. zero ohms) between the right hand pin as you look into the plug with the sensor upright, and the metal part of the sensor body. Be aware though that even if this sensor passes a static resistance test on a multimeter, it's still possible (albeit remotely) for it to be damaged. If you see any cracking in the plastic body, in particular, precautionary replacement is advisable.

i had this exact same issue, went through everything, swapping MAF's over as i had a spare, took of knock sensor, inspected it for cracks, cleaned it all up retorqued etc, cleaning up all earths/contacts, everything & anything that had been mentioned on here as a possible cause to this intermittent issue on MY99 cars. still got it. so purchased and replaced the knock sensor - hasnt been seen since!

when the error code appears, it means the signal from the sensor is duff it does not mean you are getting knock. though when the CEL is on the car will be in limp mode and splutter hesitate etc if you attempt to boot it

Thanks gents, I'll see if I can get it checked on a mates multi meter first but be prepared to change if necessary. Will also take it easy until the issue is sorted.

On a my99 car where is the sensor and how is it replaced? All I know is that 98-00 cars have a different one to earlier models.

Thanks. :)

Bump for an answer as to where it is. We can have a go this weekend, weatrher permitting, then.

its located below the ISV - you can get at it without the need to remove the inlet manifold just remove the intercooler, just need a decent socket set with knuckle joint. - youl'' need to remove the nuts on the waterpipe bracket but wont need to actually remove hoses or anything

also torque for refitting is 18lbft/25nm - fit a small washer the same size as the metal ring on the knock sensor so that the bolt doesnt not tighten against the sensor itself as it can cause the plastic casing to crack

also, a magnetic extension type thingy is handy for getting the bolt in & out as its very fiddly - ie you just cant lift it out with your fingers

info on this topic will show you its location on a bare block - so that you know what your looking for:-

https://www.scoobynet.com/general-te...ck-sensor.html

This will help

http://i877.photobucket.com/albums/a...1978/knock.jpg


Jura

Hmm thanks guys, think I'm armed with the information I need now. Will investigate :)

You got access to a small enough value torque wrench?

I could turn up a washer for you on the lathe.

I don't think I have mate, no torque wrenches round here and getting one from work would be a struggle too. :wonder:

Hi, what i did was disconnect the sensor, use a long extention with the socket.

I had to move a few coolant lines out of the way then removed the sensor. cleaned the area where the sensor is going to sit as much as i could then replaced the sensor. It was a bit fiddley but got there in the end.

I nipped up the bolt by feel as i didnt have a torque wrench for the value needed. But it has been fine since.

Thanks for that. I've managed to borrow a torque wrench from work so will try cleaning it out tomorrow and do an ecu reset to see if it comes back. If so a new sensor will be bought.

Well after having the intercooler off today with Jeff (Alcazar) I've decided than rather try remove the old rusty looking knock sensor and try refitting it after; I'll buy another one (new from Importcarparts) and fit this as a matter of course. Will do an ECU reset of the Scoob again and then test for fault codes afterwards.

Hopefully a simple enough job to switch old sensor for new - and haven't had the CEL on since I started this thread.

Maybe watch for it again after doing the ecu rest, THEN buy one if you see it again.

Invest what you save in a some decent tools;) Or another couple of toys for Isaac..........

:thumb:

Gonna go take her for a drive to warm her up and reset the ECU in a carpark somewhere. :)

You wanna see my locker at work - shiny! All polished spanners and everyfink :p

Its when its damp weather conditions itll show the cel then go off after about 30secs of driving due to airflow round it drying it. Ibought a 2nd hand one. New ones are expensive!

I may have one here, you can have it matey if I can find it.

Very kind offer fella.

Well took her out and for a warm up drive. The CEL came up for a few seconds but midway through the drive, i.e. not from cold start up. Just turned off again as ramdomly as it came on. Car drove fine still so took to a local industrial estate. Did ECU reset by connecting black & green, drove the car, CEL flashed. No fault code, just a constant flash. Unplugged and drove the car a little bit, thehnturned off and connected just the blacks together... constant flash, i.e. no knock sensor code.

So drove home with a bit of boost, drove fine. CEL didn't come up any more.

Kinda stumped now as to the randomness. Could it maybe me a MAF or lambda sensor instead? I'm still wondering whether to change the knock sensor as a matter of course because of this code and it's randomness of appearing.

Ta.

its the knock sensor trust me

:thumb:

I think it's best to replace it in all fairness.

Well just ordered a genuine knock sensor from Import Car Parts as I don't trust the eBay ones unfortunately.

I took the Scoob for a drive last night and the CEL was coming on more often and the boost is getting affected now. Would this maybe suggest a duff MAF as well or could the knock sensor put the car into limp mode periodically? The CEL was coming on more frequent but not flashing, say every minute or two for about 30-40 seconds. The car hesitates when giving it beans sometimes, sometimes not, regardless if the CEL is on.

I'm gonna fit the knock sensor properly tomorrow and then see if the hesitation carries on.

Thoughts welcome,

Thanks. :)

if the MAF is duff it'll be duff all the time, there is no intermittent MAF problem.

when CEL is on car will be in limp mode, ie keep it below 3k rpm, try to boot it etc & it splutter hesitate etc

replace knock sensor & then reset the ECU then take it a decent drive :)

This is the strange thing Gambit, the Scoob boosts fine sometimes and others it splutters/hesitates. Example was last night; car boosted fine then started hesitating, with the CEL on now and again not constant. :lol1:

Bloody thing :D

Just wondering...

Can I use an ally washer for this knock sensor? Speaking to Jeff I'm understanding it would need to be a slight "top hat" shape but he has ally only at the minute.

Ta :thumb:

Bump. Missed the post yesterday so gonna fit the sensor today. May need to buy a torque wrench too as can't borrow one today from work.

Will let you know how I get on.

Sensor now replaced. With a couple of extension bars and other hoses shifted as well as the intercooler it wasn't too bad. Torque wrench I bought was only 20ftlb but I used a precise metal washer turned up by Jeff. Intercooler is a pig to refit, well the turbo hose is a sod anyway!

Will do an ECU reset later but gonna take it for a drive now.

Don't think this issue is the knock sensor now.

Took the car out to do some bits and bobs. Engine light coming on and going off randomly. Doesn't like boost and hesitation. Got home, did an ecu reset and the knock sensor error code came up again as per my first post.

Undid the plugs, did the black ones only and it's again giving knock sensor code.

So I'm a bit stumped now. Any other suggestions?

Has it ever been mapped?

Any mods since remap or that haven't been mapped in?

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??