C1259 and C1310 still

Codes C1259 and C1310 mean that there is a trouble code reported by the hybrid vehicle control ECU. The scanner that you are using is not capable of communicating with the hybrid vehicle control ECU. You need a better scanner to read all the trouble codes that the car is trying to tell you about. You are just guessing what the problem is until you read the trouble code(s) that are in the hybrid vehicle control ECU.

What are the symptoms the car has?

 

I now see that I responded to the thread you created on January 7th, 2026, https://priuschat.com/index.php?posts/3589443

Do you have any update?

 

Brian thank you for responding to the thread, I see this is a recent one so will add and ask. I got a code reader that was supposed to also read battery information, well it doesn't. After the car (2009 Prius) needed a second jump start from the first about a week ago, the dash lit up with the red triangle exclamation, ABS, VSC, MFD had the exclamation auto. I know there are more codes but what I was able to read was C1259 and C1310. The 12v is about 2years old and is a toyota battery. So I can keep my change in my pocket, any thoughts?

 

A 2-year-old battery could be flat and cause problems if the voltage is pulled down low enough when you try to start the car.

With just about any problem in a modern car, the first step is to check that you have a good 12 V power supply. So you must check the voltage, then fully charge the battery and do a load test to check the capacity. If the battery checks out, then you can move on to the next step.

 

^+1 What dolj wrote. Charge 12v battery and make sure it is good.

If you want a better scanner. I recommend the Autel AP200. It is about $60 on Amazon. Take a look at these two threads, https://priuschat.com/index.php?posts/3248209 and https://priuschat.com/index.php?posts/3290690
Posted via the PriusChat mobile app.

 

Well I've replaced the battery, which at static consistently reading 11.7. With car on, I was getting 13.5, so it was charging but not holding. now I'll research the threads further, and there are a lot, about clearing the lights on the dash and/or how to reset to ensure accurate codes. Local shop wants $180 just to put it on and diagnose (i.e., read codes).

Just read your posts. Thank you, I'll check into the reader. Purchased reader getting overnight. They upgraded the AP200 to the 2500, still at $60.

 

From what I've read, the AP2500 is more of a downgrade. The AP200 is still available if you look a bit wider.

 

good to know, I'll look into it. I see 2500 is only 5 services while the 200 covers 19 services and actually looks more comprehensive. Well I ordered both so will return the one I don't use. Tomorrow the 2500 is in and Sunday for the 200 to arrive. I have 2011 gen 3 also, so this will be very helpful! Looking forward to learning them.

 

Be advised that the Autel AP200 and the AP2500 use two different Autel apps. Wait for the Autel AP200 to arrive and return the AP2500.

 

Thank you for the clarity. I will wait for the AP200.

 

okay...after getting the app to work correctly. I'm now dangerous, that is armed with some codes: HV Battery p0afa; Hybrid Control p3000; ABS/VSC/Trac c1259 HV Syst Regenerative Malfunction and c1310 HV Syst Malfunction; Air Conditioner B1421 Solar Sensor Circuit; and Tire Pressure C2121 id1 main and c2179 ecu communication stop.

Well, that's it. Next step, barring any input from you all, will be to identify these code sets and check live data on the HV battery. Hopefully it is only one cell and no other items. Of course I have to figure it out before going to the parts.

 

P3000 is there because of the P0AFA; C!259 and C1310 are there because of the P3000.

B1421 isn't a problem; it's a code they provide in case you want to make sure the dash solar sensor works.

The tire pressure monitor codes are their own other thing.

 

Thanks for being to the point. I'll focus on p0afa. do another read for live data on the cells. also found Error code P0AFA (2006 Prius) | PriusChat reply number 3 appears to be a good inspection check list.

 

P0AFA is a code about a low voltage reading among the blocks of the traction battery, but the key point is, "low" for this code means "too low to even be real", two volts or less, or negative. A bogus reading, then.

... which means it's really a code about the no. 2 frame wire, or about the battery ECU where the orange plug from the no. 2 frame wire plugs in. Or ill-torqued nuts, but that's not often seen unless someone's been working in there.

 

We keep it in garage about 900 miles a year since we purchased in 2019 when it had just over 100k. I did replace the 12v battery after a Toyota battery failed at about 2years, first toyota battery replaced on warranty with no warranty on replacement, so went elsewhere for the new one.

It happened as you said on V1, see file. "P0AFA is a code about a low voltage reading among the blocks of the traction battery, but the key point is, "low" for this code means "too low to even be real", two volts or less, or negative. A bogus reading, then."

I'll identify the no. 2 frame wire and check everything out.

 

Okay, I reviewed safety, including removal of the Service Plug. I need to get safety gloves and a real multi-meter. My multimeter is the free one from Harbor Freight lol. up until now, that's all I needed. Initial visual inspection show some corrosion in body area and below the orange line running forward. Tomorrow I'll have the proper safety equipment to open everything up.

 

The number 2 frame wire (votage sensing wires) connects into the hybrid battery ECU with a orange connector. I bet that you will find corrosion on some of the pins in the orange connector and on the hybrid battery ECU.


Posted via the PriusChat mobile app.

 

Okay, I've pulled the ECU and the orange plug of the ECU appears that both the 11th pins and 8th pin, clip side, have corrosion. Both white plugs of the ECU are clean and shiny. Is there a way to test the ECU, other than clean and reset everything?

number 2 wire frame connections are quite green, really deteriorated. I will be replacing number 2. haven't checked the other side yet, hopefully it will look okay. Still not sure if there is a way to check the ECU, I will definitely clean the pins.

I think I'll pick up some dielectric grease while waiting and cleaning for the part to arrive.

Adding photo of number 2.

 

Hi All, I managed to replace the wire frame number 2 and cleaned up the other side, as you could see the ecu looked really good so am hoping that I don't have to go find a used one.

I am still experiencing the two ABS codes for this thread and a NEW code for HV Battery P0A0D. Everything else has cleared except for the AC solar sensor circuit, B1421.

looks like I may have not reset the safety plug correctly? Just disconnected 12 v, will reset it and retest sometime tonight.

Any thoughts for me?