P1601:Electrically Erasable Programmable Read Only Memory[EEPROM] Error-Injector Correction Value, Diesel Particulate Filter[DPF]?

MALLYBOY

MEMBER
2009 TOYOTA COROLLA
1.8L
4 CYL
TURBO
2WD
AUTOMATIC
125,674 MILES

This vehicle was driven on a street and bounce on a bump and it off. I try to start it and it fails to start.I try to diagonize it and it was not communicating. I replace the ECM with code-free type and diagonize again and it was given only this code. I try to relearn the injectors and it says I should input 4-digit injector code. I loosen the injectors to see the injector 4-digit codes but I didn't see, so how do I get the 4-digit injector code to relearn the injectors?
I attached the screenshot of the diagnostic report below

P1601:Electrically Erasable Programmable Read Only Memory[EEPROM] Error-Injector Correction Value, Diesel Particulate Filter[DPF], Thermal Degradation Record

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Wednesday, December 3rd, 2025 AT 7:05 PM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
54,610 POSTS

On nearly all Toyota D-4D systems from this era, the injector compensation codes are NOT stamped on the visible side of the injector.

P1601 - EEPROM Data Error:

Here is what they say you need to do is, but to me it sounds like you have a shorted injector, This guide can help you test them.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Remove all injectors

1. Clean the top area
2. Capture the full calibration codes
3. Enter them into ECM using:

Toyota Techstream
Launch X-431
Autel (with Denso coding support)

The scan tool will convert the long code short 4-digit correction.

a. Relearn injectors: ECM has no injector codes stored - requires 4-digit codes
b. Looked for 4-digit markings: Toyota does not print them on injector body sides
c. Replaced ECM: Lost EEPROM injector data - P1601 appears

Please go over these guides and get back to us.

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Friday, December 5th, 2025 AT 11:04 AM