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Old 07-02-2004, 02:11 AM   #1
RyansJDMgc8
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Question Check engine light. Knock sensor. PO328

I keep getting a check engine light and the code says PO328 Knock sensor high input bank sensor 1of1. Sometimes when the check engine light is on it says this same code twice. Do you think the sensor is bad or do you think something is causeing the sensor to give a CEL? The check engine light will only come on when motor is cold. If I warm it up and clear the code, it will not come back until next time engine is cold. Also when CEL is "ON" the car runs very crappy. Feels like less fuel is going into motor. Any help?
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Old 06-28-2007, 11:07 PM   #2
jasmyer
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Quote:
Originally Posted by RyansJDMgc8 View Post
I keep getting a check engine light and the code says PO328 Knock sensor high input bank sensor 1of1. Sometimes when the check engine light is on it says this same code twice. Do you think the sensor is bad or do you think something is causeing the sensor to give a CEL? The check engine light will only come on when motor is cold. If I warm it up and clear the code, it will not come back until next time engine is cold. Also when CEL is "ON" the car runs very crappy. Feels like less fuel is going into motor. Any help?
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Old 06-29-2007, 10:23 AM   #3
Aaron'z 2.5RS
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Have you checked out the sensor? I've had mine come lose on me, throwing a code, intermitently... I've also tightened mine up aginst the block, and after a few really hot days, the case distorted and killed the sensor.... I've had a few... :0)
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Old 06-29-2007, 07:13 PM   #4
surowrxa
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Quote:
Originally Posted by jasmyer View Post
Great contribution to the thread. Thanks for coming. Be sure to post some spam on your way out.




Anyway, about the knock sensor code, I just went through this with my wife's Foerster (104K). Intermittent code, took the sensor off (it's just below the throttle body on the block), it was caked with corrosion. Some people have lightly sanded this off (and the block, with fine grit) and managed to be trouble free. It looked pretty bad, so I ordered one from SGP for $72 and haven't looked back. The car runs better and gets better gas mileage.

If you take it off (or get a new one), don't crank it down really tight. I think the specs are something like 12 lbs, which is good because the only wrench I could fit in there was the smallest sprocket I had.
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Old 10-07-2008, 02:09 PM   #5
DWMDrums
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Default P0328, P0303, P0304 - knock sensor, misfires.

I had a similar problem recently, and was able to fix it quickly and cheaply without dropping hundreds of dollars at a mechanic. I couldn't pass my emissions test because I was getting a CEL with codes P0328 (knock sensor), P0303 (cyl 3 misfire), and P0304 (cyl 4 misfire). I drive an '02 Outback Sport (5 spd, 2.5L)

Mechanic I called wanted to do a few hundred bucks worth of further diagnostics... I said forget that and consulted my good buddy the Internet.

Found on this site and on subaruforester.org some threads that hinted at some interconnection between knock sensor and misfires; many people seemed to be having similar problems, though i didn't see anyone with my exact situation. But I had enough information to conclude I should just replace the knock sensor, clear the codes, and see what happens.

I found a brand new OEM knock sensor on Ebay for 50 bucks (AutoZone sells it for about $80), had to purchase a socket extension ($4), and presto: had replaced that puppy in about 5 minutes. And I might add that I'm no mechanic. I do my own oil changes, and that's about it.

Cleared the CEL codes and I've been driving for about a week (almost 400 miles now); car is running great, no CEL, and I think I'm even getting better mpg.

Long story short, by spending a few hours online and about $60 total I was able to fix this problem myself, and so far it seems all is back to normal.
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Old 10-07-2008, 09:14 PM   #6
Bugsie3410
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I'm afraid I can't offer any answers to your original post, but I do have a question on a related topic.

I have a 2000 Legacy Brighton Wagon with the check engine light on. The error code is PO464 which apparently means the fuel meter has eratic input. The fuel guage is working fine but my Subaru garage has told me that the only way to fix the problem is to replace the fuel sender unit for an installed price of $350. This seems like a huge expense just to turn off the check engine light.

Does anyone have any experience with this issue i.e. is there a cheaper resolution?
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Old 10-08-2008, 01:51 AM   #7
Arctic Penguin
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Quote:
Originally Posted by RyansJDMgc8 View Post
I keep getting a check engine light and the code says PO328 Knock sensor high input bank sensor 1of1. Sometimes when the check engine light is on it says this same code twice. Do you think the sensor is bad or do you think something is causeing the sensor to give a CEL? The check engine light will only come on when motor is cold. If I warm it up and clear the code, it will not come back until next time engine is cold. Also when CEL is "ON" the car runs very crappy. Feels like less fuel is going into motor. Any help?
these cars are prone to bad/failing knock sensors

known issue

check to see if the bolt is tight, if not tighten it but
BEWARE---do NOT overtighten it and break the sensor!!!!!!

if not loose

replace the knock sensor, reset the ecu and good to go
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Old 10-08-2008, 02:04 AM   #8
my4isflat
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Just to let you know a good rule of thumb is if you get a DTC related to a sensor and it is a "high input" 99% of the time it is the sensor that needs replacement. If the DTC is "low input" then most likely it is a wiring issue.

But yeah, its a known issue with these cars, I've replaced my knock sensor 3 times so far.
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Old 10-08-2008, 01:08 PM   #9
Engmus
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04 STi, same code along time ago, replaced the sensor no issues since.
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