Airbag warning, then dead 12v then EV system warning

The use of my 2013 Leaf is not consistent. Some trips only go down to 93%, others go down to 50%, and occasionally a few down to 23%. It gets plugged in at night and stays plugged in until it is driven again. Sometimes it is driven the next day, sometimes it is 10 days later. I have not had any problems with the car or the 12V battery in the last 18 months. The doors unlock and it comes to life every time, with no issues.

I still have the original 12V battery in the car. I did have to top off all the cells with distilled water and charge it, when I first got the car, but have had no issues since then. The 12V battery is four years old, and will eventually fail. When it does, I'll put in an Optima Yellow Top. I may do it, as as a preventative measure, next year when the traction battery gets replaced under warranty.

I had similar experience. If I leave my Leaf unused for more than 24 hours, the 12v battery goes down. My leaf has a solar panel, and according to the manual, it should charge the 12v battery.
Few people said it maybe the ''12v charger control unit'' malfunction. Is there a way to check this ? Because the usual scanners don't detect any errors in my Leaf.
And, is the Leaf 12v battery the same as with any other non electric car, or is it different. Is there ''deep discharging'' type

The 12 volt Leaf battery is just a small "starting" type battery. Not deep cycle.

LeftieBiker said:

They may have improved the charging algorithm sometime after 2013, but it's also true that the way the car is driven seems to make a big difference. Lots of short trips seem to drain the 12 volt battery much more than regular longer ones. As for what is happening when IbLeaf2 leaves the car plugged in for long periods, would you be willing to check the 12 volt battery voltage before you unplug it one of these days?

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Sorry Leftie for the delayed reply. I only get notified of a post when I'm quoted. And just check the Active topic list when I have extra time.
So here are some numbers... plugged in at 11:15pm last night, finished charging at 2:15am, 14 hours later the battery was at 12.28V. For comparison I also checked the 2 month old battery in our Corolla which returned home at the same time last night. 12.28V is 3% lower than it was at 12.69V.
When I can, I'll check voltage before and after 24 hours of plug in time. Doesn't happen that often though. Usually I'm plugged in for 8 to 16 hours overnight. Also will check after I have a low milage day and don't plug in overnight.
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So here are some numbers... plugged in at 11:15pm last night, finished charging at 2:15am, 14 hours later the battery was at 12.28V. For comparison I also checked the 2 month old battery in our Corolla which returned home at the same time last night. 12.28V is 3% lower than it was at 12.69V.

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You are misinterpreting the small voltage drops as small drops in SOC. Anything under 12.5 volts (and 12.6 or better is preferred) is actually low. Anything below 12.0 volts, in fact, is generally considered "dead." I don't have a SOC table in front of me, but I'm guessing your 12 volt battery is at about 50-60% SOC in the above reading. So it isn't that your car is charging the battery properly, so much as that the little 12 volt battery is stubbornly refusing to die. ;-)

Well, just dodged a bullet, thanks to this forum. I had a faulty airbag warning, and took it in to service today. The told me that I had a faulty CO2 sensor, and that it would cost $3,500 to order and replace. In fact the service consultant was very embarrassed, and suggested I call Nissan Consumer Affairs to see if they could help with the cost. He ALSO told me that I needed to replace my 12V battery. After seeing this thread online, I thought I'd wait until the battery was replaced, and see what happened. Sure enough, when I picked my Leaf up, and after I started the car the and electronics cycled -- the air bag warning disappeared! The lesson: IF YOU HAVE A FAULTY AIRBAG WARNING, CHECK IF DISCONNECTING AND RECONNECTING YOUR BATTERY, AND IF NECESSARY REPLACING IT, FIXES THE PROBLEM!

The told me that I had a faulty CO2 sensor, and that it would cost $3,500 to order and replace

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Ok, this post has to be a prank! Why would an EV need a CO2 sensor, or an O2 sensor for that matter?

alozzy said:

The told me that I had a faulty CO2 sensor, and that it would cost $3,500 to order and replace

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Ok, this post has to be a prank! Why would an EV need a CO2 sensor, or an O2 sensor for that matter?

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Maybe trouble codes get reused from one vehicle type to another, so that code XYZ read from a LEAF but interpreted by service equipment set to "AMC Pacer mode" would show up as "bad CO2 sensor" instead of "charge inlet overheated"?

No prank, I assure you. I'm just telling you what the service consultant told me. I've gone and looked more closely as the docs I got, and here is what was written on my invoice: "77428 OCS (I think that's what I heard as CO2) control unit DTC stored in airbag control unit. Need to replace OCS unit and recheck. Estimate: Part #87300-3NA8A $3,012.92, labor: 2.5 $324.75 - part must be pre-paid to have ordered".

If it's the OCS, then that sounds a lot like the airbag recall:

http://www.jdpower.com/cars/articles/safety-and-mpg/recall-roundup-nissan-fix-occupant-classification-system-control-unit

https://repairpal.com/nissan-leaf-2013/recalls

If it pops up again on your LEAF, you should be able to get that fixed for free.

Thank you, that is very helpful to know.

LeftieBiker said:

A dying 12 volt battery will play hell with the car's systems, throwing all kinds of weird codes, including the ones you've seen. Disconnecting it, charging it fully, then reconnecting it may clear the codes and solve your problems, but no promises.

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I think my 12v battery is finally toast! Twice now, the GOM shows no mileage available, all types of error symbols and will not go into drive. I've attached the DTCs - just about everything. The 12v battery voltage is about 12.2 volts, however with the ignition on, it's about 11.6 volts (way low!). One time, I was able to "start" by charging briefly and then everything started normal. The second time I waited for a few minutes and it started normal.

I'm now "tender" charging the battery and plan on doing a load test after a couple days of charging (luck has it - don't need the Leaf for a few days ). I believe that battery is the original.

Any suggestions to confirm it's the 12v battery?

Those codes all look like low 12-volt battery errors.

How old is the battery? 5 years or more and you can count on it.

Yea, think the battery may be over 6 years old - likely the best battery life in any auto I've had. I'd guess the light duty outweighed the poor charging profiles.

The Japanese-built Leafs have better 12 volt batteries.

Replace the battery with a high-quality AGM deep cycle and be done with it.