Check Engine - Knock Sensor :(

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Sonac
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Check Engine - Knock Sensor :(

Post by Sonac » 21/04/19 21:38

So for the past couple days my engine has been running lean. I only drove it twice like this out of necessity and I went super easy and never hit boost, monitored the coolant temp etc. No issues.

Turns out it was just the o2 sensor wire that was shot. I replaced it and the car is running smooth on 14.7 according to my wideband. Cold start is low 13's and warm idle is 14.7-15.0 so bang on really.

Only problem is while the car was running lean the check engine light came on, I read the code as 52 which is knock sensor. Makes sense since I was lean. Now I can't get the engine code to go away.

I followed the guide on this website which said remove the EFI fuse for more than 10 seconds. I left it out for a good 30 seconds. But as soon as I start the engine and rev over 2.5k rpm the check engine light comes back. Always at 2.5k rpm.

I'm really confused as to what is causing this as my AFR is perfect now.

I'm leaving the EFI fuse out over night. I hope in the morning its fixed. If anyone has experience with this please let me know! Thanks



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Re: Check Engine - Knock Sensor :(

Post by jimi » 21/04/19 22:14

Perhaps your knock sensor is faulty, it's not unknown for knock to kill the sensor. There's a chance that running with a faulty O2 sensor, caused enough knock to kill the knock sensor ?
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Re: Check Engine - Knock Sensor :(

Post by Sonac » 21/04/19 22:38

After reading the stories on here about the knock sensor it seems you are probably right about it being broken, other people also stated that knock can kill these sensors. They are really expensive new though. Found a second hand one in working condition cheap though from a breaker. I'll probably grab that.

Seems a bit stupid that a knock sensors breaks after if detects knock though. Thats like designing a check engine light to break after it comes on once. Only a check engine bulb doesn't cost over £100.

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Re: Check Engine - Knock Sensor :(

Post by MR2DI4 » 21/04/19 22:51

These cars are now so old anything can fail. Heat and time along with vibration just degrade things. The piezo electric element is pretty fragile and its not really designed to work for a long period if your engine is experiencing knock. I would say that the sensors now pretty much fail straight away if they suddenly experience a condition bad enough required to throw an engine check light due to knock.I mean if you start hitting anything with a hammer made of crystal its going to break sooner or later.

Wouldn't waste my time with a used one, there are plenty on E-Bay that are new.

The main thing is to fix the problem with the fueling first, then chances are you will never have to worry about it again.

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Re: Check Engine - Knock Sensor :(

Post by Sonac » 22/04/19 15:25

MR2DI4 wrote:
21/04/19 22:51
These cars are now so old anything can fail. Heat and time along with vibration just degrade things. The piezo electric element is pretty fragile and its not really designed to work for a long period if your engine is experiencing knock. I would say that the sensors now pretty much fail straight away if they suddenly experience a condition bad enough required to throw an engine check light due to knock.I mean if you start hitting anything with a hammer made of crystal its going to break sooner or later.

Wouldn't waste my time with a used one, there are plenty on E-Bay that are new.

The main thing is to fix the problem with the fueling first, then chances are you will never have to worry about it again.
Yeah the fueling issue is already fixed. Its no longer running lean. I said in my original post it was just a bad wire from the o2 sensor which I have replaced. Runs really well now (other than being in limp mode). I did end up buying a sensor used since it was £25 rather than over £120 new and I don't trust those £20 Chinese ones to work. Its listed as used buy in fully working order so If I install it and the check engine light comes back then i'll just get my refund.

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Re: Check Engine - Knock Sensor :(

Post by jimi » 22/04/19 17:28

:th: Keep us updated on your progress
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