Unintended acceleration at full stop
 

I recently bought a 2017 CX 5 in mint condition, with low miles (38k) from a local Mazda dealership. Other than having to replace the original battery right out of the gate (dealership reimbursed) I’ve had no problems, and love the car.

Last night while coming to a slow stop at a red light intersection the car began accelerating. I never drive with two feet on the pedals, and am sure I had only my right foot on the break. Car kept revving higher, and higher as I depressed brake harder. It felt like it wanted to jet into the intersection, and was really frightening! This lasted for about 1.5 seconds and then stopped.

The yellow wrench appeared on the dash warning it was time to service the car. The flashing red car/lock light appeared and continues even though the car is off. I don’t remember it being on before. Coincidentally, the car odometer had turned to exactly 39,000 miles when this all happened. I remember the sales manager telling me I should service the car at 40,000.

Are any of these signs connected? I planned to service the car at 40,000 but that’s 1,000 miles down the road. I’ve read in forums now that “sudden unanticipated acceleration” has been an issue in some Mazdas. It seems really dangerous if I hadn’t been able to restrain it by pushing hard on the brake! What should I do?? I read something about returning to factory settings? Is it possible that when the battery had to be replaced it did something to the computer sensors?

Your Mazda is under warranty.

Yellow lights are cautionary lights like the check engine light
RED light on the dash means STOP. DO NOT CONTINUE TO DRIVE AND OR RUN THE ENGINE>

I highly recommend that you have your Mazda taken to a dealership ASAP.

There should be no irresponsible member suggesting that you do anything but this.

ASE

To understand this and other reading, a battery in a new vehcle is not all to uncommon that will go bad in less time than expected even if the vehicle was purchased new of the sales lot with even less the a few miles on the odometer.
Maine Reasons:
Unknown actual manufactured date of the battery
Lot boys or salesmen leaving interior lights on causing the battering to be charged. the chargers used at most dealerships are FATS CHRAGE which reduces the life of the battery.
A battery was already replaced because it failed, and the replacement was not a Mazda battery. This in itself does not mean in any way your full warranty on the battery is not honored but a failed battery can and often gets replaced with a battery other than from the auto manufacture. I am sure that if owners look in their glovebox paperwork like the tires there will be a pamphlet for the battery that is in the vehcle.

Unless he bought a new warranty from the dealership, I would think that a 2017 model year would no longer be under the original warranty. Am I missing something here?

I didn't read the first response that close and didn't even do the basic math .... LOL
See what you are saying I only saw the words recently, dealership and 38k miles so just I suppose thought there was some warranty involved? Good catch!

My CX5 is a 2017 , now with 39,000 miles. It is no longer under warranty. I bought it with 38,000 miles and it still had its original battery . The car would not start twice within the first two weeks. An inspection of battery showed it needed to be replaced at Les Schwaub. The dealership did reimburse me for my cost for the new battery. Since then the car has been fine until a day ago when it accelerated wildly at a stop light. After researching I discovered others have had similar experiences. Coincidentally, the “Service Soon” wrench symbol appeared . The dealership had already told me to service the car at 40,000 miles. But I do not remember the little red flashing light (a car and lock) that continues flashing even when the car is turned off. So I began to wonder if the unwanted acceleration happened because I changed the battery and the computer sensors were affected somehow. But the warning lights appear to be normal ….I think. I just wondered if, after changing out the battery I should have reset something to reboot the car…Could that be why it revved up with my foot on the brake in a stopped car? I was thinking of just having the car serviced for oil somewhere other than a dealership…since it had just been checked over the dealership. But I don’t know if only a dealership can check the sensors and codes etc? Anyone have experience with unwanted acceleration at a full stop?

The others you found are not the same as yours, a misconception often when seeking similar events on the internet. Unless your found an owner with same miles a duplication of al service events.

No chancing the battery does not in anyway change the drive-by-wire output information to the ECU.

The service soon symbol is set by the owner or a shop it is not related to your problem.

There are no critical systems that need resetting by changing the battery on your year Mazda.

A good quality Diagnostic scanner can access your ECU and check for current active DTC, permanent DTC and IM Monitor status. And if needed the counters


As for your last question …. A failing Drive-by wire can cause erratic acceleration behavior. But then a few other parts can as well. As I said duplication with others may claim to have been the same but all deltas would need to be the same. You might as well go to Thunder valley Casino and place a quarter in the slot machine .

Your issues/problem needs to have a experience auto diagnostics technician at least tell you what needs to be done to correct the dangerous conditions.