# P0325 clears itself, but...



## MarcMag (Sep 10, 2019)

That's what the forum reports as the knock sensor, which has triggered the CEL twice this year, back in May and today. It cleared itself each time. I've been running 92-93 octane. 

Since I have the powertrain warranty, should I take it in? If I had the Trifecta tune on the ECM, should I flash it back to stock before bringing it in? It was running in the stock tune when the CEL was triggered.

All thoughts welcomed.


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## Ma v e n (Oct 8, 2018)

Not gonna comment on running a tune or whether or not to flash back and forth for going to get car looked at....

If you set a code, and it's beyond your capability or desire to diagnose and repair then yes, obviously take it in to get looked at


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## MarcMag (Sep 10, 2019)

Thanks, Maven: I've since been told the knock sensor on our cars is particularly sensitive and two of the fixes are using a better full-synthetic oil (mine is Quaker, Amsoil Signature was recommended) and better spark plugs (but the NGK Ruthenium plugs don't come in our size). 

So maybe just an oil change when it is down below 20% life, making sure it is full synthetic and dexOS. Amazon Basic full synthetic is dexOS2 rated and about $20 a gallon, if that makes any sense.


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## Ma v e n (Oct 8, 2018)

Stock ACDelco plugs with proper gap maintained are good plugs.
High quality oil is key, I've personally usedin my car Castrol Edge and Mobil 1 Annual Protection(sadly discontinued) and will be switching to Amsoil SS most likely on my next oil change. I wouldn't run past 5000miles on Amazon or typical part store/Walmart available oils without an oil analysis. I'd run the $13.92/5qt jug of Supertech High Mileage 5w30 Dexos(probably best cheap oil there is) and change at 3k before I ran something else past 5k without an analysis. 

No matter what oil you use it should be Dexos 1 gen2 spec, and full synthetic(API SP if you can find it.). I'd recommend 5w30 even if you have an 18 or 19 model year.


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## MarcMag (Sep 10, 2019)

Thanks, Maven. The oil cap on the car calls for "dexos 0W20." Are you saying I should be running 5W30, instead? There seem to be more choices in the 5W class. 

The below are all 0W20 full synthtetic, dexos Gen2 and five quart jugs (w/o shipping or tax), using Amazon as a level playing field.

AmazonBasics is API SN Plus. $19.54
Castrol Magnatec GTX is API SN. $19.96
Valvolene Advanced Synthetic  is API SN (formerly SynPower) $23.97
Mobil 1 Advanced Fuel Economy is SN Plus and SP: $26.12 (must buy two) (slightly cheaper at W*M)
Vavolene Modern Engine is API SN Plus $39.85 and a one-two month wait (!)

My plan is to use the Oil Life Monitor and replace when life falls below 20%,


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## Ma v e n (Oct 8, 2018)

Yes it's my recommendation and opinion that 5w30 is a better choice for oil. My 2018 had it's 0w20 drained out at maybe 1000miles and filled with 5w30. Has never seen anything since. 

If you don't feel comfortable with a w30, then go with a 5w20 Dexos1 gen2. These oils are almost always a more robust less volatile oil than their 0w20 version.


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## MarcMag (Sep 10, 2019)

Thanks to Maven and Trifecta for their advice. Here's the outcome: plugs pulled and gap checked to be .025. There is not a Mobil 1 with an API SP and a dexos Gen 2 as a 5W20, so I stayed with the 0W20 and the M1 Advanced. The 5 quart jugs were $22.38 each., before the $10 rebate on Mobil's website: 2020 Mobil 1™/Mobil Super™ Rebate Program


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## HatchLifeRS (Oct 3, 2017)

MarcMag said:


> That's what the forum reports as the knock sensor, which has triggered the CEL twice this year, back in May and today. It cleared itself each time. I've been running 92-93 octane.
> 
> Since I have the powertrain warranty, should I take it in? If I had the Trifecta tune on the ECM, should I flash it back to stock before bringing it in? It was running in the stock tune when the CEL was triggered.
> 
> All thoughts welcomed.


Pretty sure the knock sensor isn't covered by powertrain but by the new car warranty (3 years/60,000km). If you're outside of that warranty it might not be a bad idea to just replace the sensor if it's relatively cheap. It's pretty easy to change. Just a pain in the butt to get to.

Sent from my SM-G935W8 using Tapatalk


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## MarcMag (Sep 10, 2019)

Thanks. I bought it as a CPO, so I'll ask the dealer IF the CEL is triggered again. Trifecta has developed another tune for it, too., in case I get the CEL if running their previous tune. I know it was running the stock tune the last time it happened.

Maybe the Mobil 1 will make a difference. At that price after rebate, it was easy to decide to try it.


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## Jgehoski1 (Jul 31, 2021)

MarcMag said:


> That's what the forum reports as the knock sensor, which has triggered the CEL twice this year, back in May and today. It cleared itself each time. I've been running 92-93 octane.
> 
> Since I have the powertrain warranty, should I take it in? If I had the Trifecta tune on the ECM, should I flash it back to stock before bringing it in? It was running in the stock tune when the CEL was triggered.
> 
> All thoughts welcomed.


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## Jgehoski1 (Jul 31, 2021)

I have p0325 code after changing fluid and running 87


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## MarcMag (Sep 10, 2019)

Since all of the above (premium fuel, the green label Mobil 1 at that rating, new tune), no more CEL. 

In fact, I'd forgotten the car even had this issue until this thread was bumped. 

MM


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