Stolen cat ... damaged ECU?

These are some of the steps I did with some questions:
Process:
1) I was able to confirm that the O2 sensor is OK, I disconnected it and reset the ECM. There was no error,
2) Reconnected the downstream O2 sensor, then P0038 appeared. It keeps appearing immediately after each reset.
3) I couldn't find an EFI relay (not Horn, IG2, or IGCT) according to the document (NiallS) provided.
4) I checked both the fuse box on the engine bay (driver side) and the Relay box in the engine bay (mid-passenger side).

Questions:
1) Are there other relay boxes in the engine bay that I'm missing?
2) If I buy an ECM from ebay, what are the programming that need to be done (beside the VIN-30 minute process)?

I would appreciate any help to pin this thing down, smog check is due in about a month.

Thanks

 

EFI MAIN is one of the four relays built into the integrated quad relay/fuse unit with the IG2, BATT FAN, and EFI MAIN fuses on top.

 

Thanks, I just looked it up. They hid that thing well

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P0038 sets when the amount of current flow for the downstream (S2) oxygen sensor heater is too high. You don't have a fault with the sensor unplugged, but do have it when you reconnect.

That makes me think that you have a bad (new) sensor. Did you use a Toyota or Denso sensor from a reputable source? (not ebay or amazon).
(edit- I reread your first post and see that dealer parts were used)

It's possible that the ECM is damaged but I wouldn't expect a "current too high" code.

If I had to work on this car, I would be using some advanced diagnostic equipment (scope + current clamp) to measure actual current and voltage in the circuit when the ECM tries to activate the heater.

That said, the ebay ECM I got was cheap, and I was able to pull the lower glove box & carefully twist the harness around to plug in the replacement unit for testing (without having to remove the old one).

PS, there's no programming or VIN anything on a Gen2 Prius- just plug it in and go.

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Solved, thank you for helping me. $25 ECM replacement worked immediately. Time to rip the dash apart and put it in. Great excuse to fix my combination meter

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You're welcome. Happy Prius-ing.

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So just and update:

I drive a 2008 prius, the ECM was from a 2009 prius (Same part number). The engine start and stop is now more like my 2015 Prius (cold start to operating temperature). Also my battery is on the green ( 1 bar down instead of 2 bar down) most of the time for the same commute. I'm assuming this all depends on the Firmware on the ECM, do I need to do a firmware update on anything else in my car to work properly with this 2009 ECM?

Also MPG has improved by 1 extra mile(could be irrelevant) and the car responds differently to the yellow intersection lights (Response time is more like my 2015).



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Most of the behavior you're talking about here would be the responsibility of the HV control ECU, not the ECM. If the HV control ECU hasn't been changed, I might be cautious about overinterpreting the behavior differences you're noticing; those can reflect a lot of things (including change of seasons).