U0100 and u0111 on Prius 2005

U codes are network commUnication problems. It is often helpful to have a scan tool that shows which ECU reported each code: the code itself means something like "couldn't communicate with X" where X is some ECU in the car, and then from which ECU reported that code, you know which one couldn't communicate with X.

The U0100 is like that. It means "couldn't communicate with the ECM (engine control module)", and there are two different ECUs in the car that might report it: the Hybrid Vehicle ECU and the Battery ECU.

The U0111 is simpler; it means "couldn't communicate with the Battery ECU", and the Hybrid Vehicle ECU is the only one that can have that complaint.

The "CAN communication system" section in the repair manual (more info) has detailed steps for troubleshooting communication issues, including some tables to focus where you start looking, based on which ECUs are reporting which codes.

 

Here is the workup for the following DTC (notice how some have supporting 3 digit INFs or secondary codes) : U0100/211, U0100/212, U0100/530, U0111/208, U0111/531, U0129/220, U0129/222, U0129/528, U0129/529, U0131/433, U0131/434, U0146 :

https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/21bpm/0100211.pdf

This image might help with locating an ECU :

 

What are you using to retrieve codes? Can it communicate with the battery ecu? Do you have codes and data from the battery ecu right now?

Posted via the PriusChat mobile app.

 

My issue was a blown 15 EFI fuse.
Might want to check that first.

The culprit that caused it to blow was exposed 02 sensor wires that were rubbing against the body.

 

When there are so many possible culprits, if everybody posted about what turned out to be the culprit in their car and said "might want to check there first", sometimes the result'd be just a jumble of things to check "first" for the next person to sort through, when they could just be following the tree of elimination steps in the repair manual. For this code, an early step is to check the +B voltage at the ECM anyway, so a problem with the EFI fuse would be caught in short order.

That said, it isn't hard to check that fuse first if you want to.

And a very common complication of catalytic converter theft is having those O₂ sensor wires left dangling under the car where they can short and blow that fuse. So certainly if there's been a converter theft in the car's history, those wires will be an early place to look.