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driving down the highway , after passing slow moving vehicle, the tpms started flashing, check charging system showed up on the mileage display, and eventually all the alert lights came on.
Pulled into an auto parts store, battery & alternator both test good. Sat through a video appointment, turned the car on and no error messages nor lights.
driving on the highway again, 70mph speed limit , and it came back on when accelerating to get into a spot in the next lane to let someone in from the on ramp.
pulled into a rest area and cycling the switch reset the error. But it came back on when hitting 75, again accelerating to get over to let someone on., and it reset again the same way.
best i can tell its coming on at speeds around or over 70 mph,
Im getting ready to look at the serpentine belt, but iirc it was replaced when we replaced the pulley on the timing system that’s known to go bad and make an odd noise on starting
anyone have experience with this kind of thing?
EDIT:
after multiple testing, scanning, etc. the following results and solution.
error code p16e2
communication error between pcm and battery sensor on negative terminal.
battery good
alternator good
solution, replace sensor
sensor cost from dealership approximately 430.00 usd
Cheap sensor available from Amazon for 17.00 USD.
bought for testing, successfully eliminated errors
https://a.co/d/5tTTB8M
EDIT 2: (04 July 2025)
the error returned, but thanks to one of the responses here, I tried cleaning the alternator connectors with electric parts cleaner, which is a good idea anyway considering that the oil fill is essentially right above the alternator.
After using an entire can to clean the alternator and the engine area above the alternator, then air drying with a fan for a few hours, then clearing the error, the issue so far appears to be resolved, even after several days of driving.
Last edited by FunkTastic; Jul 4, 2025 at 08:08 AM.
That's very odd. See if you can get the warning lights to come on, then get someone to scan it before turning the ignition off. As in drive up to the store, call them and ask them to meet you in the parking lot with the scan tool. It's also possible that the first store you went to was using a very basic scan tool that couldn't "talk" to the network of control modules in your Fit.
That's very odd. See if you can get the warning lights to come on, then get someone to scan it before turning the ignition off
I have a topdon scanner and I am home now. I will be putting the scanner on it, but I was hoping to get an idea other than the standards that the AI reports on a google search.
we rely heavily on this car and I don’t want to be driving it and have it stop working.
That MIGHT be the dodgy (bad) 2015 fuel injectors...people say all the dashlight light up. is it key or pushbutton start?...if its key it might be the ignition SWITCH..there is also some sort of battery monitor attached to the battery lead that also goes bad,.these are random thought FYI...but id search 2 of these 3 things....its probably NOT the ignition switch...someone claimed to fix the battery monitor issue by running an auxillary wire....he had strong thoughts on that. it seemed a plausible solution to me.
Last edited by 2015FITEX; Jun 12, 2025 at 08:21 PM.
driving down the highway , after passing slow moving vehicle, the tpms started flashing, check charging system showed up on the mileage display, and eventually all the alert lights came on.
check engine light was on, but going off with the reset efforts.
after putting my scanner on and monitoring relevant available data streams for the electrical system.
i see some indications that the battery is discharging intermittently but nothing concerning.
the error happened faster adding draw to the system (lights plus a/c, etc)
Checking codes before turning off the engine, the temporary code P16e2 pops and the search/help function on the scanner brings up the battery sensor built into the negative battery terminal connector.
im going to get the code to pop up again and unplug the sensor and plug it back in to see if the error goes away with that. Plus im going to try to find and check all relevant fuses.
unfortunately this is an expensive sensor, listing at over 425 walk in and 380 running it through the shop for the repairs.
this leads to another question on the reliability of parts bought from 3rd party vendors that supposedly offer oem at half the price. I can find it online at 3rd party vendors for like 170 or so and on ebay for less than a hundred.
That MIGHT be the dodgy (bad) 2015 fuel injectors...people say all the dashlight light up. is it key or pushbutton start?...if its key it might be the ignition SWITCH..there is also some sort of battery monitor attached to the battery lead that also goes bad,.these are random thought FYI...but id search 2 of these 3 things....its probably NOT the ignition switch...someone claimed to fix the battery monitor issue by running an auxillary wire....he had strong thoughts on that. it seemed a plausible solution to me.
its push button and the switch was replaced somewhat recently, the same time the timing pulley issue was repaired.
Don’t think we have done any work on injectors but I would think those would throw codes.
do you have any information on running the auxiliary wire? I would like to research this for safety and efficacy to use while we’re looking into getting replacement parts.
Last edited by FunkTastic; Jun 14, 2025 at 04:36 PM.
The sensor in question monitors battery current, voltage, and presumably state of charge. Sort of a battery health monitor. It communicates via a LIN data link (a one-wire serial communication spec). The code appears to be complaining about losing communication. Check inside the connector at the sensor for contamination, inspect the wire from the connector back to the harness.
If you opt to replace the sensor, go to a pick'n'pull - I would expect $20 tops. Vehicle fitment is 2015-2017 Fits and 2016-2022 HR-Vs.
Cleaning all the battery terminals sounds like a good start also, like i said,there is a post of someone with a similar problem who ran a wire from alt to battery + i think, he claimed it fixed it
The sensor in question monitors battery current, voltage, and presumably state of charge. Sort of a battery health monitor. It communicates via a LIN data link (a one-wire serial communication spec). The code appears to be complaining about losing communication. Check inside the connector at the sensor for contamination, inspect the wire from the connector back to the harness.
If you opt to replace the sensor, go to a pick'n'pull - I would expect $20 tops. Vehicle fitment is 2015-2017 Fits and 2016-2022 HR-Vs.
the picknpull is a good option but we haven’t found one in driving distance that has a compatible vehicle.
I did find a cheap one on amazon that has reported success initially that might be worth it just for a tester.
Cleaning all the battery terminals sounds like a good start also, like i said,there is a post of someone with a similar problem who ran a wire from alt to battery + i think, he claimed it fixed it
i did clean the terminals and connectors. No change
The sensor in question monitors battery current, voltage, and presumably state of charge. Sort of a battery health monitor. It communicates via a LIN data link (a one-wire serial communication spec). The code appears to be complaining about losing communication. Check inside the connector at the sensor for contamination, inspect the wire from the connector back to the harness.
If you opt to replace the sensor, go to a pick'n'pull - I would expect $20 tops. Vehicle fitment is 2015-2017 Fits and 2016-2022 HR-Vs.
couldn’t find a pick n pull with a donor vehicle
bough the cheap one from Amazon and it’s working. Will continue to look for a pick n pull while using the cheap aftermarket.
edited, original post with info in case it shows up in searches in the future
Clean the cable to the alternator with some electrical contact cleaner and then use a zip tie to hold it on tight. Drive it for a day and the lights and check charge system message will go away. I had the same problem and this and this fixed it.
Clean the cable to the alternator with some electrical contact cleaner and then use a zip tie to hold it on tight. Drive it for a day and the lights and check charge system message will go away. I had the same problem and this and this fixed it.
Clean the cable to the alternator with some electrical contact cleaner and then use a zip tie to hold it on tight. Drive it for a day and the lights and check charge system message will go away. I had the same problem and this and this fixed it.
I wanted to provide an update and expound a bit.
Im cautiously optimistic that this is a decent solution.
After driving the car again a couple days later, the error came back so I decided to try this first. I used a full can of cleaner on the connectors, carefully targeting anything that might be at risk from the oil fill and then set up a fan in the engine well to let it dry for a couple of hours.
Regitar/ebay sells voltage regulators. Regitar you need an account, worth it. Ebay runs about 50-70? With shipping? Currently running a regitar and very pleased with it. Alternator disassembly was not hard. Way better than $350 for a new alternator. More people need to learn to repair, new cars are gonna be a big issue without.
