Bleeding Brakes – Less Fluid from Front vs. Rear? Codes C1364/225 & C1365

I’m using Techstream to air bleed my 2008 Prius brake system. My setup is a vinyl tube running from the bleeder screw into a Gatorade bottle to catch the fluid. I’ve noticed that the front brakes spit out much less fluid than the rears during bleeding.

I’m currently dealing with C1364/225 and C1365 codes, which indicate the front right wheel pressure sensor is reading lower voltage than spec. When I clear the codes, the brakes work perfectly—so I’m confident it’s an electrical or computer issue, not a mechanical one.

I’m trying to figure out if the problem is:

1. A dirty, corroded, or blocked bleeder screw (restricting flow but still letting air out)
2. A dirty, corroded, or collapsed brake line
3. An issue with the ABS/wheel speed sensor
4. Moisture or damage in the ABS motor relays
5. A failing ABS pump/brake actuator

Here’s what I’m seeing:

• Front brakes: Very little fluid comes out compared to the rears. With Techstream, I have a helper pump and hold the pedal, then I crack the bleeder. First time, lots of bubbles in the bottle; second time, fewer bubbles; third time, no bubbles. This pattern is the same for both front wheels.
• Rear brakes: Lots of fluid comes out, and I watch for bubbles to stop before tightening the bleeder. Both rears behave the same way—lots of fluid and bubbles at first, then clear.

Background:
I replaced the ABS pump two years ago with a used unit. It was a budget fix, but it worked. However, after every heavy rain on a hot day, the codes would return. I’d bleed the brakes with Techstream, and the codes would go away—until the next hot, rainy day. I eventually realized I hadn’t fully bled the front right wheel, and once I did, the problem disappeared for a while. Now, the codes are back. I’ve bled all four corners thoroughly, three times, but I’m still getting C1364/225 and C1365.

Questions:

• Is it normal for the front brakes to bleed less fluid than the rears on a Prius?
• Has anyone else seen these codes come and go with weather changes?
• Any advice on what to check next, or is it time to replace the actuator again?

Thanks for any insight!