Auto stop/start function not working



I’ve read many disparaging things about “auto-stop” technology and its real-world fuel savings.

The article I read (and I forget where I read it, so take with a grain of salt) claimed that these devices work great when the battery is brand-spankin’-new, but as soon as the battery becomes a bit used, the battery has trouble maintaining charge the way it used to, and the “start/stop” feature is used less and less, with less fuel savings.

Remember that the MFR’s goal isn’t to burn less fuel, per se, it’s to get a good score on the EPA Combined Cycle test. (And in this case, on the EU test, which favors start/stop a lot more than the EPA does.)


This is one example where tests are mis-used.
Another is the offset frontal collision test, the carmakers only add protection to the drivers side of the body.
Another in public schools, the teachers teach the kids how to take the standardized tests instead of a balanced education.


No direct experience with that technology, but during my daily walk-abouts here in my San Jose neighborhood, I notice newer looking cars quite frequently come to a stop and the engine shut offs, then start up again when they leave the intersection. So it isn’t that this function hardly ever works. But in a colder climate, given how cold affects a car’s battery, it might not work as well in the winter as it does in the summer.


I have a 2015 Jeep Cherokee with the 3.2L V6 and this vehicle also has the start/stop feature. I have had some minor issues with this feature and there are 2 main reasons. The first is the engine needs to be warmed up completely in order for this feature to work. Related to this, if the climate control is on (especially the air conditioning) it drains the battery more and the feature takes more time to become active.

The other main reason is the engine control software. Sometimes there is a needed update which, when completed, will allow the feature to work correctly. In addition, I once had to have a number of software updates installed at the same time and the feature did not work for 2 or 3 days until all the updates learned to play well with each other.

Overall I’m very satisfied with this particular feature. My vehicle is EPA rated at 19 city and 26 highway mpg. My driving is mostly urban but my overall average is just under 21 mpg.


I’m also wondering if the system keeps the engine running intentionally in cold weather to keep it at operating temperature. I would think that for emissions purposes it would have to, colder engines producing more emissions like they do. Anyone know the answer?


The owners manual states that high heat or air conditioning demand or use of the defroster will disallow auto start/stop operation along with about ten other reasons. Engine and catalyst temperatures are also factors but not published in the owners manual.


Good point about the cat converter temperature. The catalyst has to be hot to do its job too.
I’m convinced.


You’ll be satisfied up to the day you spent $600 to replace the starter.



Some longer trips seem to have restored my battery. The Stop/Start function now works, even when the headlights are on. Perhaps this truck sat on the lot a long time & the battery lost charge. Hence, when we bought it, the dealer had quick charged it, but that hadn’t restored its deep capacity. Our longer trips might have allowed the truck’s charging system to charge the battery correctly. I’m now pleased with this function. Manufacturers have used it for years. The technology might now be perfected.

Bob Gillespie


Glad your F150 is working as advertised again. Appears there wasn’t actually anything wrong w/the stop start function, just doing what it was supposed to do b/c the battery was a little drained. Thanks for the update.


I too thank you for taking the time to let us know the problem was resolved. We so rarely hear back from original posters as to what the final results were.

Happy motoring.


lol … Reminds me that I’ve posted quite a few times for a poster’s fails to crank problem suggesting to measure some voltages at the starter motor. I don’t think I’ve ever heard a response back saying that worked or that it didn’t work. What happens seems like the poster just disappears. I presume they got the no-crank figured out somehow or another, otherwise they’d come back for more help …


Hi I’m late to this topic but I had issues that escalated a couple of weeks ago with the start/stop on my 2015 jeep - took it to the dealer and the constant start stop kills the battery! hmmm guess they didn’t think about that when they put that feature on the car. so they replaced my battery - no charge - and so far everything is back to normal! we had noticed for a while now that we were having issues with hesitation to restart at intersections, then the lights kind of blinked - a friend who has same vehicle - her car shut off at a stop sign and would not start no matter what she did! her car is going in friday and I’m pretty sure she’ll be getting a new battery too! :frowning:


If the battery was that weak it needed to be replaced, with or without auto start/stop you need a good battery in your vehicle.


agreed but I haven’t even had the car 3 years - I got it in July of 2015!
my friend has exact same issue and got her car same time - waiting for Friday to hear what they tell her!


Batteries - Some last a long time and some don’t.


Another bad idea that people seem to gob onto. I would not buy that feature if I had a choice and if I had to have it, I would disable it if I could. In Motor Trend (I think, already threw it away) Bob Lutz talked about all the glitzy features being put into cars that do nothing for the driving experience. Talked about when one company comes up with a new idea, the others feel compelled to follow suit regardless of what customers want. Why we have touch screens instead of knobs anymore.


Can’t you push the eco mode button to disable it every time you start? Yeah, it’s a hassle, but life’s tough…



3 year old batteries are nearing the end of their life for most any car, especially if the car is a daily driver and driven in hot climates. Fails-to-crank is probably the most frequent complaint we get here, not just from auto start/stop owners, but from most everyone. The cause is usually some combination of the battery connections/battery/starter motor. Many car owners who live in hot climates replace their battery pro-actively at the 3 year mark. Cheap insurance against the risk of a no-crank in bad weather, bad neighborhood, etc.


if you do the research - I forget the timeframe - but a normal car stops/starts 50,000 - this fuel saving feature that Jeep has put on the vehicle, ups the stops/start to 500,000! of course it will kill the battery but no one said that. all they did was tell us how much fuel we would save NOT that in 2 1/2 years - that’s TWO AND ONE-HALF years, I’d have to buy a battery - seriously! And the problems related to that feature - car stops suddenly, car won’t restart, computer doesn’t work correctly, can’t activate the button to override the stop/start AND the stop/start causes extreme wear tear on other parts of the car not just the battery! I’m sorry I didn’t know this up front but now that I know it, when this lease is up - I likely will not get another Jeep!