ABS, Traction & Parking Lights + Sulfur Smell + 28 Communication Codes!

I have a 2012 Prius II with around 246,000 miles. Very little maintenance needed so far, and I bought it at 110,000 miles about 5 years ago. I drive a lot.
I had all 4 wheel bearings replaced last fall. Immediately afterwards, my traction control, ABS, and Parking light came on. Cruise control failed to work and braking was a bit spongy. They took it back and said it was due to some wiring (maybe wiring harness?), fixed it, and the issue went away until earlier this summer. All 3 lights popped up several times since, but other than the failing cruise control, there were no performance issues. Then, at one point several weeks ago, the cruise control was intermittently deactivating itself but no warning lights popped on initially. Only after several occurrences did the ABS, traction, and parking lights come on. I followed some directions found on here and shut down and restarted the car several times until the lights went away. Then we completed the trip without further incident.

Last week, the codes randomly popped up again while driving. (And they always pop up while driving; they're never on immediately upon starting the car.) Except this time, I smelled a sulfur-like smell. I thought it might be due to possible fireworks while going through a small town (I had the windows down with no AC on), but the smell only got stronger a mile or two outside of town. I stopped and found that it was coming from the front right side of my car. A passerby stopped and also smelled it very strongly from 50 ft away. We searched for any obvious signs of a problem and couldn't see anything. No dripping of fluids underneath either. Even though it wasn't having any other performance issues, I opted to have it towed to a local mechanic rather than drive it home.

The local mechanic stated that it had 28 codes stored, and claimed that most of them were communication codes. They checked the connectors, looked over the wiring and speed sensors, and didn't notice any issues. They tested the 12V (only at my request; they hadn't thought of it) and said that it, "tested 30 cca below rating (less than 10% low). do not see a date code but it looks like it could be OE."
The codes that displayed were: C2315, P1578, U0129, U0140, U1107, C1466, C1467, U0073, U0123, U0124, U0126, U0293, B2311, B2311, U0142, U0155, U0131, B2784, U0129, U0293, U0131, B1585, U0129, U0140, U0293, U0073, U0129. (There are some duplicates that I kept in the list intentionally.)
The shop cleared the codes and told me to "try it." Unfortunately, I took it home, parked it, then started it the next morning. The ABS, Traction control, and Parking Brake light were on upon starting (a first). I don't feel comfortable driving it since we obviously haven't found what the issue is.

I suspected that it might be the 12V battery, but they shop tested it and said that it was fine. And I don't want to throw money at something that might not fix the issue. Does anyone have any clue what areas to look at? I have an appointment scheduled to take it to the Toyota dealer next Wednesday, but we all know how $$$ they are. Any advice would be much appreciated! Thank you!

 

Update: The dealership stated that the intake manifold needs replaced and that a speed sensor is causing the codes. They claimed that the manifold is causing the sulfur smell.

Codes are: P0303 and C1467

My car was also due for a software update, which they did for free.

On the way to the dealership (before any diagnostics), the ABS, traction control, and parking lights went off while in transit. The lights were on upon picking it up, then went off on the 1.5 mile ride home.

 

Regular maintenance like oil changes and tire rotations, yes. And anything else that comes up in between (minor or major repair). The spark plugs were all replaced 2 years ago. I had several misfires at that time (started and ran rough, so I know the sound now). Spark plug replacement took care of it.

 

Quick update: We haven't made an appointment to do anything yet, but I will have to on Monday. We drove it around about 5 miles and the smell of sulfur/burning plastic is VERY strong.

 

Update: My non-dealership mechanic does not agree with the Toyota assessment regarding the intake manifold. The wheel sensor was a no-brainer, so unfortunately that hub will have to be replaced as the ABS started acting up on the 0.5 mile drive there.
The mechanic said that he's going to look at it this week and give me a call back if he can figure out what it is. He doesn't want to replace a part that isn't bad or the cause of the issue.

 

Update: Local mechanic drove my car 30 miles before he could "smell" it, and couldn't identify the smell. Now he has someone else driving it around. Now I'm concerned that they're going to ruin my car..

 

Update: Mechanic said they couldn't smell anything. These guys must be heavy smokers or something because I have two other people that did notice it. Anyway, I told the mechanic today that I needed an answer or I'd have to move on to another shop. They've had it for a week this time, and a bit longer than a week from the previous time. My backup vehicle just died on me so I'm in quite the pickle... I also asked the mechanic to look at the EGR and clean it and the manifold out.

Anyway, we picked up the car 4 hours later and the mechanic claimed to have cleaned the EGR. I don't think he actually cleaned out the manifold. He said that there was some buildup in the EGR, but not enough that he thought it was the issue. He also reconnected a wire around my wheel that fixed my spastic ABS sensor (that had started to lock up the car while driving). I drove the car maybe 5 miles around town with the AC on full blast. No smell! Then hit a little dip/bump right as I drove up to my place and BAM! Sulfur smell in full force. Is it possible that that bump knocked some older material loose in the EGR or IM and that caused the smell? I'm going to test drive it again tomorrow, but I may have to just bite the bullet and get the intake manifold replaced. I've spent $350 on diagnostics at this rate. I'm still making payments on this car, too, and I really enjoy driving it. I'd love to continue doing so rather than trading it in.

 

Yes, I have actually. It's coming from under the hood, on the right side of the car. Somewhere in the middle of that area. I can smell it while driving with the windows down as well as when the AC is on. I couldn't get it to recreate the smell while just running the EV mode. Going to test engine only tomorrow, but I have a feeling that it's only happening when the engine is running constantly.

 

Update!
We found the problem! The front right (passenger) headlight bulb had come slightly loose and melted the plastic ring/bracket that it was secured into. The air intake for the car is right behind that headlight, so that would explain why the smell was so strong.
We didn't make the connection of "smell=lights on" because, after a few weeks, all of the exposed plastic in that area of the bracket had been melted. Only when braking would we smell it after that, and that's because the inertia of the car caused the light to make contact with more of the surrounding plastic, and release fumes. The mechanics likely drove it without the headlights on, so it wouldn't have been burning.
I've ordered a new headlight because that plastic piece is too far gone, and it doesn't look like that component is sold separately from the headlight assembly.

I'm still battling ABS sensor issues, so I guess unplugging and plugging in the wheel sensor didn't work long term. I'll have to bite the bullet and get a new wheel bearing in the rear wheel. But otherwise this case appears to be closed.

Thank you all for your help and suggestions! I'm glad that we didn't go with Toyota's suggestion (although the intake manifold did get cleaned). It wouldn't have solved the problem.
Thanks everyone!