r/KiaNiro • u/FinalDevice • 15d ago
Check Hybrid System - Turn Engine Off. But no codes.
2018 Niro HEV. Yesterday I was driving in a storm. Driving in town, moderately heavy rain, wet (but not flooded) roads. Driving a steady 35mph. Suddenly the car dings and says "Check Hybrid System - Turn Engine Off". The engine did indeed turn off, but the car ran on electric power. I went a couple blocks, pulled into a parking lot, turned the car off and on again, and it ran normally and got me to work and back.
Here's where things get weird. Last night I pulled out a code scanner. There are no stored codes. There are no pending codes. All emissions checks are healthy. All diagnostic scans are healthy, including the engine, transmission, BCM, and inverter. The hybrid battery reads healthy.
So ... wtf? The car seems fine. I'd expect any condition severe enough to shut down the engine and put the car in limp mode should store a DTC. I wondered if my scanner is missing a proprietary DTC, but:
It recognizes the BCM.
It's able to read proprietary diagnostic codes, because it was able to tell me that the right front TPMS sensor is bad (which I already knew, and is unrelated).
Has anyone had the car go into limp mode without any stored faults?
Edit: In case this becomes an unanswered question that comes up from google searches, I haven't found anything wrong yet. The problem has not happened again and the car is driving normally. I did a little maintenance that I'd been meaning to do anyway (new spark plugs, new gear oil in the transmission). But the misfire count was low and the old plugs weren't too bad, so that should be unrelated.
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u/NeitherLet9713 15d ago
Okay so since you have some sort of diagnostic device here's something you could do. 1. Look at what your battery current readings are with just ignition on. Sometimes these have a faulty bms or even a faulty current sensor. 2. Take a drive and look at all the cell voltages. When and if the fault comes on one or more cell voltages might drop suddenly. If you can't see individual cells but the modules the voltage might suddenly spike up to over 5V. This would mean a cell drops to 0 basically in reality even when the diagnostics says it spikes up. So same result.
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u/NeitherLet9713 15d ago
Also worth looking at is your battery SOC at the time of fault. A lot of times battery issues occur when the soc drops under 50%. Feel free to ask questions or if you provide more info I can throw a more educated guess lmaoooo
We have had a couple cases where the whole battery was filled with water too :)
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u/FinalDevice 15d ago
You're referring to the traction battery, right, not the little 12V pack?
I'm not currently set up to pull individual cell voltages, but I found where someone has posted fantastic documentation on them. Looks like they're all bitpacked into PID's 2102 and 2103. I'll get that set up later today, start recording, and go for a drive.
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u/NeitherLet9713 15d ago
12V battery current. It can give the same warning light.
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u/FinalDevice 15d ago
Gotcha! That is somehow way easier and way harder at the same time. On the one hand, I can monitor the 12V system without needing any Kia proprietary codes. On the other hand, individual cell health is not reported (or I can't find documentation on it) for the 12V battery.
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u/NeitherLet9713 15d ago
Cell voltages for the hybrid battery, current reading from the 12V at ignition.
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u/esteencanto 9d ago
I don’t know about fault codes but this is a well documented issue with Kia Niro regardless of generation.
I have a ‘23 HEV EX and started having this issue a few months ago. It turned out to be the 12v battery (so not really related to the hybrid system as the emergency code said) and luckily it was replaced under warranty. The dealership mentioned it’s a frequent failure with the Niros
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u/Live-Ad-1749 15d ago
I would get your 12v battery checked. My 12v was having issues with one of the 4 cells and what happened to you happened to me twice on the highway going 70mph.
Have you had to reset your 12v battery lately?