Image below from my PCM reader.
2010 Mazda 5, 155k miles.
Got 4 different codes (1 of them twice), but the common denominator seems to be an electrical issue. Anyone see such a thing and know where best to start fixing it? Could it be as simple as needing a battery or alternator?

 

At least one of those DTC if you are asking on a forum to diagnosis it then you would be far better off to go to a service shop in your area. There are several in the Dallas are that employee ASE Certified Technician's which is really who you want to work on your car and especially with those series of codes.
Thes codes relates operation having more to do with the transmission and that is primarily why an experienced hand should be looking into the causes of the trouble codes and not simply clearing them and hoping they don't return.

I would also suggest NOT to discount the battery (power source) until you know exactly what caused those DTC's

 

I can appreciate having a legit mechanic working on it, but that gets expensive real fast and I'm broke :P I've been doing a lot of my own mechanic work since I was a teen, but a lot of those vehicles were of the "Pre-PCM era" of cars. I'm not ASE certified by any means, but I have some experience. I'll go to a mechanic if I really have to, but I'm trying to avoid it.

I failed to mention at ALL these code happened at once; the service light lit up and I scanned for the codes 2 hours later without the van being driven in those 2 hours. I've looked at the possible issues for those codes and most list something electrical as a possibility. Ultimately, I'm curious if anyone else with a Mazda 5 has had this happen and what the fix was (whether it be by home repair or mechanic). It seems strange that so many issue would happen at once if there wasn't some link, or something missed.

 

OK let me put it another way.... Your ECU will generate trouble codes starting with P. Those I can walk most people through or point them with a good HOW-TO resolve them.

Most all other DTC (i said most) like a U series diagnostic code are not user friendly without the proper professional level diagnostic scanning device and updated software. Mine is a Solus.
You may have noticed I highly recommend not to lose the power supply or disconnect the battery even to change it without first diagnosing the codes you got. The only exception is if you use a power supply to the system that aloows for 12volt power when changing a battery.

I will state this again .... without experience and specialized training to diagnosis some codes you could damage systems that will cost more to repair then what the actuals original cause of the that specific DTC was.


The sequence or timing of how many were generated although is always information to pass on it is not necessary any values to suspect anything without doing the proper diagnosis tree of testing and eliminating in a very specific order.
Heck I can pull the coil pack on all 4 cylinders and spin the engine for a few seconds re install the coil packs and start the engine and have no less then 5-6 DTC all at one time.

 

P0661 is usually the vacuum solenoid going bad. Cheap enough aftermarket and reasonably easy to replace.

P0841 I would delete and see if it comes back.

The two U codes are purely communication codes and are generally not worried about.

 

Thanks, I'll start there and see what changes.

 

Do Not Disconnect the battery for any reason until you resolved the problem.
Use a Scanner connected to the OBDII diagnostic connector to properly clear/reset the DTCs.
You will need to do at least a minimum of 3 drive cycles to see what if any DTC return even if one appears quickly with less than those drive cycles.

** DO NOT DISCONNECT THE BATTERY to clear/reset DTC. **MYTH
Disconnect the battery on OBDII ECU systems only turns off the dash indicator alerting of a DTC it does not clear the ECU memory of the DTC if it is a not anomalous DTC.
OBDI and earlier ECU engine code use that method to reset the ECU and trouble codes in some ECUs (not all ) of that time period. CAN-bus and OBDII are different!

 

I promise I won't disconnect the battery. I hadn't even planned on doing so.

 

Ok I worry about you. LOL
Did I see you posing your issue on another forum... haha!
Here you get 2 things,
no guessing BS from DIY members lol
and GrimeReaper is certified MAZDA Technician, and I am 40 years as a ASE Master Technician. Both of us are current.

 

lol, I appreciate the insight of experts. If you saw this issue posted elsewhere, it wasn't me. This is the ONLY place I've posted about this issue.

For what it's worth, there are (were) 2 mechanics in my family. 1 has been retired for 10+ years and the other is rookie (tech at dealer ship for 3 years). Both live out of town now, but I did have someone to check my DIY work year prior, and slap me in the back of the head if I was going to do something stupid. Both only had the insight I already knew since they couldn't see the vehicle (list of possibilities, and the "U" code is unique), hence my coming to a Mazda specific forum for insight before I sink any time and money into it.

As for the vehicle in question. I did clear the codes yesterday to see if anything comes back, and it did when the wife took it to the store today (first drive since clearing). I'll find out what came back when I get home this evening.