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Guest Message by DevFuse

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95 2.2: Cleaned MAF Sensor, now getting knock sensor code

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5 replies to this topic



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Posted 24 April 2012 - 06:29 PM

I cleaned the MAF sensor on my 95 LEGOBW with CRC MAF spray. The sensor looked fine before and after the cleaning. The car wasn't running poorly, but I had the spray, and it was easy to do. At the same time, I pulled off the PCV valve and cleaned it out. It appeared to be fine, clicking back and forth like it's supposed to. Lastly, I sprayed some of the CRC MAF sensor cleaner in the throttle body, while I had the air inlet pipe off. Buttoned it all back up and it ran fine.

Next day, get a Check Engine Light (CEL) for a P0325 code, for the Knock Sensor. I had the code cleared, but it came back in about 20 miles of highway driving. The car runs fine, just slow, as usual.

So, what should I check? I wasn't getting the P0325 code before I did the cleaning, so I don't think the Knock Sensor is bad.

Thanks, y'all.

#2 98obster


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Posted 24 April 2012 - 08:32 PM

i would clear the code and if it comes back you probably need a new knock sensor. they do go bad (~100k). not sure why you have a OBDII on a '95 but that's my diagnosis.

#3 WoodsWagon


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Posted 24 April 2012 - 08:36 PM

The knock sensor and MAF are completely unrelated, so I think the knock sensor code happening after your cleaning was probably chance. The knock sensors do fail, many of them have cracks in the plastic they're cast in. It's relatively cheap and pretty easy to replace and it's one of the main sensors the computer uses to optimize power and efficiency.

Check the connectors under the throttle body that are attached to a bracket coming up off the bellhousing to make sure you didn't disconnect or yank on the wires when you cleaned the throttle body.

All 95 legacys are OBDII. It wasn't legally required until 96, but a few manufacturers switched over early.

Edited by WoodsWagon, 24 April 2012 - 08:39 PM.

#4 Fairtax4me



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Posted 24 April 2012 - 10:49 PM

Knock sensor is bad. All too common on these. Just a coincidence that it happened after you cleaned the MAF.
Here's some help on replacement:

#5 Recian


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Posted 25 April 2012 - 06:38 AM

Yep happened to my 95 too. It was melted when i bought the car at 130k. Seems common. I put a oem one in at $95. Theyre pretty easy to change or mine was and i have 0 knock now even under heavy loads. My car has obd2 also. Its mandatory for all 96 and newer vehicles but some companies put them in as early as 93 to test them and make sure they functioned properly by the mandated date in 96.

#6 Rooster2


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Posted 25 April 2012 - 02:09 PM

Yea, I very recently replace the knock sensor on my '95, 2.2 motor. They do go bad. It is not the easiest to get at, but with perseverance you will be able to swap it out. A bad knock sensor causes reduced gas millage, and engine power.

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