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Discussion Starter #1
2011 Sonata gls with the 2.4l engine. Car runs fine, knock sensor update has been done several months ago. I added my daughter to my car wash account and every time after a car wash (it does wash the underside) I get the check engine code for the knock sensor, get home reset it and it's fine until the next car wash. The engine plastic covers under the engine is intact as well. Never had an issue with rain or degrea sing and rinsing the engine off.

I'm guessing somehow the wiring is getting wet. I bought a new knock sensor to replace and figured some dielectric grease would solve the problem. Trouble is I can't find the knock sensor on the engine and YouTube was no help unless it was the smaller accent again.

Any advice and or location of this **** thing?
 

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I have never seen a knock sensor affected by water but I have seen O2 sensors get filled with water and log codes. Post up the code number. Can't help with location but most cars it's around the bore area. Perhaps someone else knows the exact location.
 

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So the first update for the 953 campaign is just software. If knock issues come up, they will replace the harness with proper protection from other interference. If the harness hasn't been replaced, then take it in with the CEL on.
 

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Discussion Starter #4
Code is P0325-knock sensor.
I thought about calling the dealer and asking what was done to it. I'm guessing software only.
 

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Is the undercarriage cover on?
 

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2011 Sonata gls with the 2.4l engine. Car runs fine, knock sensor update has been done several months ago. I added my daughter to my car wash account and every time after a car wash (it does wash the underside) I get the check engine code for the knock sensor, get home reset it and it's fine until the next car wash. The engine plastic covers under the engine is intact as well. Never had an issue with rain or degrea sing and rinsing the engine off.

I'm guessing somehow the wiring is getting wet. I bought a new knock sensor to replace and figured some dielectric grease would solve the problem. Trouble is I can't find the knock sensor on the engine and YouTube was no help unless it was the smaller accent again.

Any advice and or location of this **** thing?
It's on the front of the engine, many months back posted a pic of the location - I believe it is drilled into the block, just below the cylinder head. So I would wager it's more likely to be the harness - which has had interference issues on some cars and requires a new harness, knock sensor itself is usually very reliable.
 

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Discussion Starter #7
1 the cover was on when it started. I took it off looking for the sensor which I believe is under the intake that's why I can't understand how it's getting wet. My daughter went thru the car wash with the cover off and drove to the dealer and of course the code didn't occur. Dealer ran it thru their wash several times, even sprayed water underneath and nothing. Next time it happens they said to drive it in limp mode to the dealer so they can document the code and then bring it back for service.
 

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You're not alone with this issue. My 2012 Sonata was a great car until the 953 update. After throwing the code on the way home from the dealer, I took it back and they replaced the sensor and harness. I now get the code every time I wash the car (and only after the car wash). I've found that it usually takes 1-3 days for whatever is wet to dry enough to return to a well behaved car gain. This has happend 3 times in the past 6 months. My dealer really isn't trying very hard to identify the issue and is only going by the Hyundai book as if the sensor is really identifying an issue, when the car wash seems to be the trigger. Please update if you ever find out what is getting wet and causing the code to throw.
 

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Time for another #Me Too movement! I have a 2018 Santa Fe Sport, and had the initial software update done when it was going on 1 year of ownership. Not too long thereafter (at approx 12K miles) came my CEL-limp home moment and a trip to the dealer. This happened about 30 seconds after leaving a car wash w/underbody spray.
The dealer installed a new wiring harness... mid July 2019.

Fast forward 2 and a half months. Again- Check Engine Light and limp home mode. Guess what?? -I had just left a car wash with the undercarriage spray! It’s back at the dealer now and they just called, telling me they are replacing the knock sensor.

I had asked if they had any other reports about a carwash being a possible trigger. No such reports, but they DID make a note of it. I’m going to share the info on this forum with them. It’s good to know I’m not the only one!
 

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Time for another #Me Too movement! I have a 2018 Santa Fe Sport, and had the initial software update done when it was going on 1 year of ownership. Not too long thereafter (at approx 12K miles) came my CEL-limp home moment and a trip to the dealer. This happened about 30 seconds after leaving a car wash w/underbody spray.
The dealer installed a new wiring harness... mid July 2019.

Fast forward 2 and a half months. Again- Check Engine Light and limp home mode. Guess what?? -I had just left a car wash with the undercarriage spray! It’s back at the dealer now and they just called, telling me they are replacing the knock sensor.

I had asked if they had any other reports about a carwash being a possible trigger. No such reports, but they DID make a note of it. I’m going to share the info on this forum with them. It’s good to know I’m not the only one!
Well good if it's fixed for good, not good if it happens again owing to a less than perfect product improvement campaign. Did they actually determine that the knock sensor was faulty or just replace it as they do with the hiring harness in a sequence of fixes. I wouldn't rule out that the noise of undercarriage spray machinery produces sonic energy that triggers a cel, I've not been to an auto car wash in years but recall that they are noisy.
 

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Well good if it's fixed for good, not good if it happens again owing to a less than perfect product improvement campaign. Did they actually determine that the knock sensor was faulty or just replace it as they do with the hiring harness in a sequence of fixes. I wouldn't rule out that the noise of undercarriage spray machinery produces sonic energy that triggers a cel, I've not been to an auto car wash in years but recall that they are noisy.
I just got the Santa Fe back yesterday, and my dealer had been very thorough. Their paperwork explained exactly what they did (including removal of intake manifold to get to the sensor}: 1- Tested knock sensor (performed interference test): FAIL. 2- removed bolt to sensor, then reinstalled and retorqued. Tested sensor again: FAIL. 3- Installed new sensor and retested: PASSED.

In a day or two, I'll run it through the car wash again and see if anything happens. Oh, and for what it's worth, I had taken this car thru this car wash dozens of times over the past year with the underbody spray. Never a problem until now, so whether or not it affected a failing knock sensor- Who knows?
 

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I just got the Santa Fe back yesterday, and my dealer had been very thorough. Their paperwork explained exactly what they did (including removal of intake manifold to get to the sensor}: 1- Tested knock sensor (performed interference test): FAIL. 2- removed bolt to sensor, then reinstalled and retorqued. Tested sensor again: FAIL. 3- Installed new sensor and retested: PASSED.

In a day or two, I'll run it through the car wash again and see if anything happens. Oh, and for what it's worth, I had taken this car thru this car wash dozens of times over the past year with the underbody spray. Never a problem until now, so whether or not it affected a failing knock sensor- Who knows?
Thanks for the update! I've had 2 instances of the CEL/Limp Mode right when leaving the car wash. But also had it again a week ago during rain. This is the first rain triggered instance though. Planning to drop it at the dealer in a week or so to have them test the sensor and harness that they have already replaced before.
 

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The knock sensor alert triggered while i was driving in the rain, and engine light started flashing. Not sure if it has to do with pressurized water as mentioned in another comment. It's less than a month they added a knock sensor as a part of upgrade/recall. Took my car to the dealership and they charged me a huge diagnosis fees which is a lot for this stupid company upgrade. The diagnosis results came out - bad knock harness, duh! the upgrade in itself is a problem. I don't know what to do if it happens again. I think it will be a big issue trusting my car, and paying Hyundai dealership every time their upgrade fails.
 

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The knock sensor alert triggered while i was driving in the rain, and engine light started flashing. Not sure if it has to do with pressurized water as mentioned in another comment. It's less than a month they added a knock sensor as a part of upgrade/recall. Took my car to the dealership and they charged me a huge diagnosis fees which is a lot for this stupid company upgrade. The diagnosis results came out - bad knock harness, duh! the upgrade in itself is a problem. I don't know what to do if it happens again. I think it will be a big issue trusting my car, and paying Hyundai dealership every time their upgrade fails.
did you contact Hyundai and ask them to intervene and have make the diagnostic fee n/c ? it's after all entirely their fault - not yours .
 
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