jestevens

I think the CVT in the C-MAX and Prius are more reliable compared to the ones from Nissan for example -- it's just unfortunate they had this seal issue. I do love the car, a lot of hybrids come with upmarket trim because the car cost a lot more than a gas car at new. I'm very satisfied with my purchase but bought the car used with 30k mi around 2016 or so so I've been able to enjoy it for quite a while.

The 2nd Gen Prius batteries are starting to fail now, but they also use Nickel Metal Hydride chemistry, I think the C-MAX uses Lithium ion -- so far I've only seen a handful of cars reported on here saying "Stop Safely Now" -- someone with the Forscan app and an OBD dongle might be able to see the actual degradation in the state of charge on the battery pack.

The charging routine typically only allows using between 20-80% of the ACTUAL battery pack range to help preserve the battery for as long as possible. Charging to 100% or discharging to 0% is a sure way to lower the life expectancy of the battery so the battery management software is programmed to avoid it. This is all seamless to the driver, the difference is programmed into the gauges, etc.

Maybe you can at least test drive the C-MAX and see what you think .. I really like the car .. It's a lot better than the competition, which at the time was the Prius V -- (had absolutely NO power). Ford was more interested in selling F-150, Escapes and Fusion and seemingly took some government funding to develop their version of the transmission and a few other components. They oversold the car as getting 60MPG -- on a very good day, with just the right driving the car CAN do that but it's more typical to get around 40-42MPG.

It was TRW that actually developed the drivetrain concept way back in the 60's but up until now they just never had decent enough batteries to make it a reality.

Yeah, that's not normal -- I would take it to the dealer to diagnose sooner rather than later before you have a serious problem on the road.  If it is expecting power to be there from the hybrid system and it's been disabled, either because of the HV battery or transmission malfunction ..

Hybrids work best with low rolling resistance tires -- although a few of the ones I've bought over the years seem to start at 7/10" tread so you're paying a lot and getting less tire?  That formulation makes it easy to get up to speed and then be able to coast around town.  If the tires are too sticky then you aren't going to be able to coast on electric only and save gas.
 
I've used Goodyear Assurance Fuel Max tires, Bridgestone Ecopia EP422 Plus and Pirelli Cinturato P7
 
I would recommend the Goodyears again -- or the Ecopia tire if you can find them (although they seemed noisier).
 
Currently I am using the plain Goodyear Assurance tires WITHOUT the fuel max -- which ARE stickier than usual, and do cause the car's drivetrain to shudder with sudden stops .. That's what the dealership had in stock that day and I thought maybe they would eventually wear down to 7/10 anyway.  There is a slight hit on MPG.
 

old one above.  New one:
https://www.tsbsearch.com/Ford/22-2396
 

Heard that Ford finally "owned up" to unresolved tranny issues (through 2018s).  Sadly, not a recall (yet), but at least a TSB:
https://static.nhtsa.gov/odi/tsbs/2018/MC-10148717-9999.pdf
 

I've only heard of like one battery pack that has seriously failed so far. . Having said that if the car is 10 years old and has say 150k mi on it you might need to expect to spend at least $5k within the next 5 years to replace the pack. 
 
There are some Prius cars with 10+ years and at least 200k mi that failing but those packs are NiMH .. the C-MAX was one of the first hybrids to use lithium ion packs so it's still a bit of a guess as to how long they will last. Batteries kept in the same environment as humans will last longer. Battery sitting outside in the AZ sun or used as a taxi, not so much ..

The problem with that might actually be lack of use. If the battery is left to discharge for a long time you might have other issues, but a low mileage 2017-18 from a climate that's not overly hot or too cold might maximize your longevity.

If you have another Ford dealer available I'd try them.  I recently bought a second 2016 C-Max Energi with 59k miles and it has a low roar/howl under load my first 16 with the same miles does not.  The dealer I use has a Shop Foreman who has a 2017 C-Max as his personal vehicle. We drove the car and he diagnosed it as the pinion in the final drive going bad - the dealer is replacing the transmission.  The Energi has an 8/100k warranty on the powertrain including the transmission (in CARB states like California it's 10/150k) so don't accept one opinion.  The C-Max should be very quiet if it's right.  Good luck. 

You may need to take the car in to get it scanned by Ford..  it's hard to say with no diagnostic codes.  Another person recently posted similar .. maybe transmission issue or if you are lucky maybe a brake switch ?
 
I say because it's bucking without you hitting the brake but it's all speculation until you get some codes.

To clarify, the more accurate way to gauge the battery health of these vehicles is to see the actual kwh used from a full charge. There's no other way. Ford doesn't have any internal data points on these indicating battery health. Don't rely on the 'miles of range' the vehicle gives you as this can vary significantly depending on certain factors and isn't an accurate depiction of battery health.
 
Here's a brief rundown of the test process:
 
1) Fully charge to 100%
1a) (optional: Reset a trip meter before taking off)
2) Drive the vehicle in EV mode ONLY. Do not drive on the highway or use cabin heat/defrost or anything else that may cause the engine to start. If the engine starts during this test, the numbers are immediately invalidated.
3) Once the battery is depleted and drops to hybrid operation you can either view the kwh used on the trip meter or bring the car to a safe stop, shut it down, and view the trip summary displayed.
 
5.5kwh is what is considered brand new capacity from the factory. Above 4.0 is still 'good/ok'. Anything less starts getting into solid degradation.
 
Anecdotally: My 2013 with 90k miles is around 3.5kwh or so capacity now. It still drives with no issues and nets me in the range of 12-15 miles on a good day.

Once the plug-in charge is depleted, it operates like a hybrid only model which still charges/depletes the battery as you drive as part of the hybrid operation. But it won't come up to having a plug-in charge where you can run pure EV mode, hence the 0km range shown.

Actually there is. Many owners of newer model years have confirmed this on the FB C-Max groups. My 2013 didn't have it initially but I was able to add it. Need to go through the BCM Central Config in Forscan and there's a Global Open/Global Close option. It may need to be 'toggled' to get it to work, ie: If it already shows Global Close enabled, switch to something else like disabled or Global Open only, save/write, then go back in and repeat the process with Global Close enabled.

Indeed, as it turns out I got screwed in the rear driver's side tire last weekend. I could not feel it by hand.  A local shop plugged it for free.

Indeed, as it turns out I got screwed in the rear driver's side tire last weekend. I could not feel it by hand.  A local shop plugged it for free.

It was about $250 for the drain and fill.

I took the car for a long drive on back roads today to charge the battery and try out the transmission.  No issues so far -- other than a low tire pressure warning.  Pulled over to check and the back tires were low .. one about 10 psi and the other about 20 psi .. no punctures .. I don't know if this is because it was sitting on the rack for a while, or maybe the crazy temp swings we've been having here in the Northeast US.  I filled them back up and they've been fine since.

There are multiple different pumps used on HF35s in various applications. This one is specific to the Energi.

I had dealer shop complete the shift cable bushing fix and drain and fill the transmission at @ 123K mi today .. they didn't notice anything peculiar in the fluid, so far no issues.

The 12-volt battery doesn't do much when starting a hybrid - it doesn't have to crank a starter like in a conventional vehicle. When mine died (2018, 5 years old at the time) I happened to have a 12-volt sealed lead acid battery lying around from a computer UPS that failed, and even with minimal charge, that was enough to start the vehicle - at which point the high-voltage system supplied enough power to keep the 12-volt system up, so that I could drive to an auto parts store to get a replacement. 

now the proud owner of a 2015 cmax energi...
 
out the door taxes, tags, titles, ect  11400
 
same color too.  now just  need ot learn how best to squeeze mileage out of the enrgi.  drive to work is only 18miles.  so I should be seeing some pretty good fuel numbers....

I have had this happen multiple times over the life of my C-Max (2013 Energi, now with 76,000 miles). Fortunately, it has only ever happened at home, so I've always been able to jump the car. And then everything is fine again. Sort of. 
 
The first times it happened, my Ford shop told me I needed a new 12v battery -- and they replaced it. Fair enough.  Not long before the problem happened again. I thought perhaps it was because we'd left seat heaters on, or a fan on, or radio, or something. We did get a small clue, that the radio wasn't working. My Ford shop couldn't find anything, anywhere in the Ford system. The next time it happened, I pushed harder, and the dealer searched the Ford tech service bulletin (TSB) network in search of responses/solutions from other techs anywhere worldwide who might have encountered and dealt with the problem. 
 
Long story short: they found one TSB notice and used it to completely reboot all of the car's software (don't ask me exactly what systems) -- a process that took about 3 hours. And that has worked great for a couple of years. This last time, a couple of months ago, my wife told me the radio had stopped working. Fearing that this was a warning of what was to happen, we left the car out of the garage to make it easier to jump. Sure enough: in the morning the 12v battery was dead. Another jump, and it was OK, but after driving around a bit to get things charged again, the radio still wouldn't come on -- until suddenly half of the central SYNC screen lit up, the radio half-started, the rest of the screen filled in, and the radio was back -- as if it required a set voltage from the battery before it would work work properly. 
 
Have just taken it back to the Ford dealer. This time, they told me they replaced the APIC -- the radio module. They did this for free, so I'm not complaining; the car is way past warranty. But I'm not convinced the problem won't happen again... 
 
S-o-o-o:  two takewaways there:  1) consider the whole system reboot (which may be under warranty for you); and 2) consider the APIC radio module if you're getting the same warning sign of the radio going dead before the whole battery goes dead. 
 
Hope this helps some folks. 

5 days from my Escape's first anniversary, 16K miles, and aside from several minor recalls (rearview camera, A-pillar trim, PCM update), the car's been perfect. Some owners have had severe problems (stop safely now) which (I think) were addressed by the PCM update. I never saw them. No SYNC issues, and my NAV update installed flawlessly. 
 
My only complaints revolve around the block heater. The factory installed the heater, but failed to install the harness. Dealer got it right on their third try, after I pointed out to my service writer how block heaters on their diesels were installed. It now sticks out of the bottom grill. I'm controlling it with a networked switch, and finally realized I should use the scheduling feature - Ford recommends a 3 hr. run - so it runs long enough. My memory always reminds me too late; no point in a 30 min. run.
 
Of course, the C-Max performance was similar... the bomb had a 100K mile fuse. 
 
Stay well,
Frank

First, there is no 12 V battery under the hood.  The 12 V battery is located under the floor in the hatch area.  The big High Voltage Battery is also in the back.  Which battery did you have replaced under warranty? 

To start your car,  the 12 V battery needs to be able to power up all the control modules in the car.  The control modules then run checks to insure your car is “ready to drive” which primarily means that the HVB is properly connected to the High voltage system and the control modules are functioning.   Your car will not start if the HVB is not properly connected.
 
When your HVB is plugged in and charging from wall power, the 12 V battery is also being charged by a separate 12 V charger only used when car is plugged in and charging.   When the car in in “ready to drive” mode (HVB is connected), the 12 V battery is charged from the HVB by a DCDC converter module (there is no alternator like a conventional car). When car is off, the HVB is not connected to the HV system.
 
It sounds that you have a significant 12 V battery drain causing the 12V battery to completely discharge  in a few days.  The APIM behind the radio / display has been know to  cause battery drain.  You can try pulling fuse 79 in the fuse panel located under the glove box and leaving it out over night and see If battery drain stops.  Put it back in when you plan on driving car. 
 
Here’s a document you can read and learn a lot about the hybrid / Energi.
 
OBDSM1700_HEV.pdf
 
 

Update on my issue: after having the car for a day and a half, service manager contacted me.  It looks like the sound I heard was indeed the bearing/transfer shaft issue and they're replacing the entire transmission under warranty!  It appears that being under 8 years/100,000 miles with the extended coverage on the Energi was what made the difference.  It should be replaced with the current (mid 2015 and later) HF35 transmission.  Should take about a week to get the part and get it installed.  In retrospect, getting the first gen (2013 MY) of this new transmission was a risk, but I knew it wasn't an entirely new design, just an evolution of the earlier design so I thought I'd be good.  I vaguely remember the extended plug in hybrid warranty powertrain coverage being an incentive to buy, and it looks like I wasn't wrong.  This service experience makes me more likely to look at a new Mach-E as my next car, I'll tell you that . . . definitely heard from Tesla owners that the service experience is awful.  

In 2013, we became familiar with the Engineering Test Mode function in the left hand display.  But until recently we were not quite sure how to convert the ETM DTCs to the standard OBDII codes.   The ETM display shows Diagnostic Trouble Codes (DTCs) as stored by the modules in the vehicle in Hexadecimal format in 6 bytes of data.  One can convert the 6 bytes into the OBDII DTC formats.  Below is an example of how to convert.  Assume C46B86 is displayed in the ETM. 
 
1) "C" hex = 1100 binary,  first two bits 11 = Network Code U, second two bits = 0 in hex.  So, the first two (OBDII) digits are U0. 
2) The next three bytes after the "C" byte are the same in OBDII format. So, the OBDII DTC is U046B.
3) The last two bytes in the ETM code are used to better define the DTC and are attached to the OBDII DTC with a ":".  So, the C46B86 ETM code becomes U046B:86. 
 
The first two bits of the first Hex digit can be 00, 01, 10, or 11 binary where
00 = P for powertrain codes
01 = C for chassis codes
10 = B for body codes
11 = U for network codes
 
However, I don't recall ever seeing and Powertrain, Chassis, or Body codes in the ETM from any poster. I have only seen the first Hex digit being a "C" or "F" which are U DTCs.  This leads me to believe the ETM only shows U codes.  But I could be wrong.  If anyone has seen P, C, or B codes in the ETM please post. The first digit of a powertrain ETM code should be either a HEX  0, 1, 2, or 3 digit so  OBDII P0A2D - Drive Motor A Temperature Sensor Circuit High = 0A2D in the ETM and P1289 - Cylinder Head Temperature Sensor Circuit High = 1289 in the ETM.   Here's an example of an "F" ETM code.  
F00316 = U3003:16
U3003:16 Battery Voltage: Circuit Voltage Below Threshold

Issue in summer sounds like clogged evaporator core drain.  Do you use MAX Defrost to clear windows in colder weather or turn A/C on in cooler temps to remove humidity?  In MAX Defrost, AC will operate if outside air is above about 35.6 F. Do you have a panoramic roof?  It's simply held in place with a sealant.  Perhaps sealant is damaged.  My guess is, if panoramic roof leaked, water would be channeled to the pillars much like rear window washer hose leak.