Crank no start after replacing transmission?

Tiny
PETE CORBETT
  • MEMBER
  • 2003 SUBARU OUTBACK
  • 3.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 130,000 MILES
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!
Thursday, February 26th, 2026 AT 1:49 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,428 POSTS
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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Friday, February 27th, 2026 AT 7:47 AM
Tiny
PETE CORBETT
  • MEMBER
  • 4 POSTS
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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Friday, February 27th, 2026 AT 11:10 AM
Tiny
KEN L
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  • 55,428 POSTS
These are grounds but no the ones I am talking about, they will be at the bellhousing of the transmission up high.
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Saturday, February 28th, 2026 AT 9:30 AM
Tiny
PETE CORBETT
  • MEMBER
  • 4 POSTS
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!
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Saturday, February 28th, 2026 AT 2:56 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,428 POSTS
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
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Sunday, March 1st, 2026 AT 11:00 AM

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