P1605-00 + U0100 - Rough Idle / Fuel Rail?

Curious what thoughts folks have on next steps for the above codes. I do not have a CEL and overall don't notice the truck running differently, however I've seen the U0100 before in historical codes. Using OBD Fusion, I randomly checked all DTCs across all components this morning and was surprised to see, especially the P1605-00 code. I do tend to experience more misfires than many trucks, especially when cold but most are undetectable and rarely exceeds 10 (normally 3-5) which means no CELs have ever been triggered.

I'd not worry about it except for the fact that I'm at 57,000 miles and want to ensure I don't have some sort of ticking time bomb that will conveniently grow into a more major issue as I exceed the Toyota powertrain warranty.

Seems this code is due to rough idle or perhaps fuel rail pressure depending on where I search, but the FSM indicates it's related to rough idle. And I've seen some comments from years ago in the 2nd gen forum indicating that if you only have a P1605 and no other active codes, the ECM / computer needed to be replaced.... Help me prevent a costly repair post-warranty

 

Bump...

 

All I could find.

https://www.engine-codes.com/p1605_toyota.html
P1605 TOYOTA Possible Causes

• Air Leak in Intake System
• Faulty Mass Air Flow (MAF) sensor
• Faulty Engine Coolant Temperature Sensor
• Faulty Fuel Pump
• Faulty Throttle Body Assembly
• Faulty Engine Control Module (ECM)

https://www.obd-codes.com/p1605
Toyota P1605: Knock control - malfunction Cause: ECM

So looks like you may have a faulty ECU. I would use Techstream to pull that code as it'll give you more details than OBD Fusion.

 

thanks! I’ve actually seen a historic code for the ECU stored before but without any other codes so it seemed to be random, but with the new addition of P1605 and no other active codes it does seem to point to ECU - from what I’ve seen on the 2nd gen forum it seems that if that code isn’t accompanied by any other codes it’s likely an ECU issue.

Now the big question is whether I’ll get help from the dealer given it hasn’t illuminated CEL but I do not want to have to shell out for a new ECU after my 60k...

 

Just ran a report on my truck from OBD Fusion and found a historical code for UO100 as well.

...I know this isn’t helpful; just wanted to share.

I’m not going to worry about mine, but interested in how it works out for your truck.

 

I think I read once, the apps themselves can cause those codes.

 

Interesting. When I have a bit of time over the weekend, I plan to hook up to Techstream and take a look at the freeze-frame data. I'm not as concerned about the U0100 - I've seen it before and cleared it b/c it didn't seem like a big deal on it's own. The "rough idle" is a new one though so I'm hoping some freeze-frame data was captured.

Regardless I'll get it at least documented by the dealer, such that if anything fails (assuming they don't diagnose and fix - they won't without a CEL is my guess) at least the code will be documented to give me some basis for a good will claim w/ Toyota down the line. this along with all of the other issues I've had with my truck just have me more paranoid than I'd normally be as I approach expiry of the PT warranty.