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BooSTIng
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Discussion Starter · #1 · (Edited)
Hey all, so as many of you know I recently got my STi back from being built. All is perfect with the car, running great and smooth and I couldn't be happier. However, like the title states, I keep getting this darn CEL code of p0852-Neutral switch input circuit high. The first few time it came on, it went off after turning the vehicle off and then back on a few minutes later. Now when it comes on, it is staying on. I called andrewtech about the issue, and they never pulled the transmission out of the vehicle, or messed with anything where the switch is. (the switch is located on top of my 6 speed MT transmission, towards the back of the tranny). However, Andrewtech said that they would take care of the issue and fix it when I bring it down for the 1k mile service. The problem is, having a CEL drives me crazy!!!

I have been driving myself crazy researching the code, and there is a little bit of info out there, but not a ton. Seems to be on the rarer side of CEL's. I did find one thread that gave me a way to test the switch using my accessport. Apparently, this code means one of two things. 1) the switch above the clutch is bad, or 2) the actual neutral switch on the transmission is bad. To test these I started with the clutch switch first. There is a gauge on the AP that is something like "clutch switch". When running this gauge, it will show either on, or off. Depending on if the clutch pedal is pressed in or not. This worked fine. Indicating and changing to on/off as I compressed the clutch. Check that box, that isn't it. So I then switched the gauge to the "neutral switch". Same thing, it will indicate on/off when the car is in neutral, or in gear. Now with this one, no matter if I was in gear, or neutral the gauge just showed "off". Bingo! I am pretty sure the switch itself needs replaced.

Now my questions is, has anyone ever had this CEL? Or performed this replacement? It looks like a PITA from what I can tell. I ordered the new switch from Subaru and it will be here Wednesday. I just don't know if I should try myself, or just deal with the CEL until I take the car to Andrewtech on the 3rd and have them take care of it. I just don't know if it safe to drive the car with this CEL on or not. Any help is appreciated!
 

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Super Moderator
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Mine did it a couple times in a row when I pulled the battery, but it went away.

The switches could also be sending an intermittent signal. When you pull a motor transmission or not wires can get moved and pulled. Trace the wires and see if one is pinched or rubbed raw.
 

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BooSTIng
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2,253 Posts
Discussion Starter · #3 ·
Yeah that's what andrewtech said. More than likely a wire somewhere. But the switch from Subaru is a special order item for my STi. I went ahead and ordered it that way I have it if needed. I don't want anything stopping me from getting on the dyno on September 3rd.
 

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Yeah i don't blame you, I'd want that thing as fast as i could get it at this point. I'd genuinely be surprised if it was either switch. They are not exactly items that fail
 

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BooSTIng
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2,253 Posts
Discussion Starter · #5 ·
Several threads I have read said they just replaced the switch, and never had a problem again. The new switch was only 30 bucks from Subaru. Might just have them replace to make sure. See what they say once they get it on the lift there and take a look.
 

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Your build is why I'm still here. I'm waiting for a video of you having that Jeremy Clarkson Ariel atom moment.
 

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BooSTIng
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2,253 Posts
Discussion Starter · #7 ·
Too add to this, I found out this morning that my reverse lights are also not working. No other CEL other than the p0852 mentioned above. Which I believe is only for the neutral switch. Now I am wondering if it isn't a wiring issue. Maybe they missed a plug putting the engine back in the car or something...... I'm lost.
 

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If they are going to fix it if just try to ignore it. If you can't ignore it, follow Dem wires
 

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BooSTIng
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2,253 Posts
Discussion Starter · #9 ·
Forgot to update this. I replaced the neutral switch itself and it did not fix the problem. So I took it to andrewtech to have them look at it. Come to find out, at the connection from the neutral switch harness to the main harness (on the main harness side) the wires were frayed. Not sure what caused it, if from maybe it sitting outside in the cold weather when it was broken down, or something else. But andrewtech fixed the wiring at no cost to me, and it has been perfect ever since with no problems.
 
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