crank no start after replacing transmission?

2003 SUBARU OUTBACK
130,000 MILES • 3.0L • 6 CYL • 4WD • AUTOMATIC
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PETE CORBETT
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I just replaced the transmission in my 2003 LL Bean h6 3.0. extremely hard to find, so it's a used transmission. now it cranks but no start and threw 2 codes, ECT and a knock sensor high bank 2 code. fans run constantly with key on. I replaced the ECT sensor and have the same conditions but it threw an additional crankshaft position sensor code. does this sound ECU related? car ran great before transmission replacement. I thought I wouldn't have to have any reprogramming done on this year of car, am I wrong about that? I did a basic reboot, but same problems. Thank You!
Feb 26, 2026 at 1:49 PM
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STRAILER
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Most of the time the problem will be that one of the main computer grounds has been left off, can you see any grounds wires that do not have a home? I checked out the wiring diagrams and there is a ground at the right rea of the engine that goes to the knock sensors. Check it out and let me know what you find. Check out the images (below). Ken
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Feb 27, 2026 at 7:47 AM
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PETE CORBETT
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I’m pretty sure these are the grounds that you are talking about. They look good, undisturbed. I am unfamiliar with the dotted loops on the wiring diagram, does that mean the sensors are grounded through their threads? I noticed that each knock sensor only has one wire going to it, while the crank and ect sensors have two.
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Feb 27, 2026 at 11:10 AM
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STRAILER
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These are grounds but no the ones I am talking about, they will be at the bellhousing of the transmission up high.
Feb 28, 2026 at 9:30 AM
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PETE CORBETT
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I got it! One of the electrical connectors with a bunch of wires that goes into the firewall was connected, but I didn’t have it snapped all the way tight. Boneheaded mistake by me. I can’t say thank you enough for putting my mind on the right track. What an invaluable service you guys provide, and not behind a pay wall, which seems super rare these days. Much appreciated!
Feb 28, 2026 at 2:56 PM
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STRAILER
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Glad you found the problem, I have seen that before so it is fun to help out when I can, please use 2CarPros anytime we are here to help. Can you please leave us a rating?

https://g.page/r/CZdEnyCkGgm6EB0/review

and

https://www.sitejabber.com/reviews/2carpros.com

Thank you! Good old fashion people helping people. Ken
Mar 1, 2026 at 11:00 AM