What does engine code 12 signal?

Tiny
CREWINBRUIN
  • MEMBER
  • 1993 TOYOTA PICKUP
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 218,000 MILES
Last evening my engine stopped with a slight thud while getting off the freeway. No bad smells, engine didn't turn over trying to restart. Check Engine flashed code 12 when I jumped the terminals.

Some information I've found suggests it's the knock sensor that's the issue. Others say it's something within the distributor, and a new distributor is in order.

93 22RE 2.4L. Wondering if anyone else has any experience with this while I figure out what to replace.

Recently adjusted the valves and the mileage dropped a bit. And there was a "put put" noise at lower RPMs if that helps
Tuesday, July 8th, 2025 AT 12:07 PM

4 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,185 POSTS
Code 12 - not receiving the signal from the distributor pickup coil, but this can be because the timing chain let go FYI, how does it sound when cranking, like flipper? It also sounds like the valve is too tight which can put extra strain on the timing chain. If you upload a video of the engine cranking, I can tell you for sure if the timing belt is good or not. If the timing chain is okay, I would get a rebuilt ignition distributor which you can find on Amazon for $77.00.

https://amzn.to/44AfnWb

Let us know how it goes.

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Tuesday, July 8th, 2025 AT 3:55 PM
Tiny
CREWINBRUIN
  • MEMBER
  • 3 POSTS
Thanks for the advice. I checked under the valve cover, and the timing chain is still solid. When I gapped the valves, I went with the Yota tech advice of making them slightly tighter 0.007 instead of 0.008" and 0.011" instead of 0.012".

Getting a new distributor from O'Rielly's because I need this rolling asap. Will adjust the gaps accordingly.
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Tuesday, July 8th, 2025 AT 6:47 PM
Tiny
CREWINBRUIN
  • MEMBER
  • 3 POSTS
Update: The timing chain snapped. My sorry self managed to drop a 16mm bolt into the engine last time the valve cover was off, and I didn't inspect things soon enough. Sitting right there on the bottom gear. I'll be taking the cover off and putting a new chain in ASAP.
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Tuesday, July 8th, 2025 AT 8:23 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,185 POSTS
Don't too hard on yourself, it happens. I need to say there is a good chance you have a bent valve or two FYI. Let me know if you need help with any of the repair.
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Wednesday, July 9th, 2025 AT 5:50 PM

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