Hi Naverick, I know it has been a while since you posted this, but, I was wondering how you got on. I live in Ireland and have a 2015 Mazda3 Skyactiv 2.2 diesel. I think I had a similar experience. April 2023 my car stalled in traffic (doing about 10-15 kph) and wouldn't restart. I had no power steering, no assisted braking and had to be pushed off the road. I still had electrics and the starter motor was working but it wouldn't start. I had it towed to the local Mazda dealer and they had it for a few days and said it needs an engine carbon clean. That was done and everything worked OK.
Like various places in the world, Ireland had a recall back in January 2020 for concerns that carbon could build up in the intake shutter valve (some call it a throttle body but in the Skyactiv 2.2 it is used to shut the engine down efficiently when you turn off the car). I received a call from my local Mazda dealer (at the time of the recall) to say that I had to bring in my car for work to done on it. I'd never experienced a recall before and they didn't say it was a recall. They said it probably needed a carbon clean and if I had to pay for it myself it would have cost €1200. It was like they were implying that I got a "free" carbon clean.
Fast forward to April 2023 and my car stalls in traffic and needs a full engine carbon clean. I thought it smelt fishy and that's when I found out about all the details of the January 2020 recall. Mazda Ireland called it the AK016A recall. I found out that the carbon clean was done (when required), the intake shutter valve was inspected and replaced if necessary and an engine software update was applied to help prevent carbon build up.
I questioned the dealer after my research and under protest we payed for the carbon clean (at a reduced rate as we got Mazda Ireland involved) as we needed the car back. I wrote to the dealer and Mazda Ireland stating that the stalling and subsequent carbon clean was the same as the 2020 recall and that we shouldn't be paying for it as the problem arose again. The recall didn't fix the problem. No modified part was placed in the vehicle and only a software update was applied. Both dealer and Mazda Ireland said my car was old (2015), mileage too high (142,000 km) and my driving style was to blame. They said that it had nothing to do with the recall. I am still in dispute with them via the Department of Transport in Ireland.
It looks like you had a similar problem to me. Just to note weeks before the car stalled I had a low oil pressure warning light come on. Towed the car to the dealer. Sump dropped, sump strainer changed and they said it was water in the strainer. I now think it was probably blocked with carbon deposits. Cost me €450.
The scary thing is that in Ireland the recall wording said that the carbon could cause your car to stall. In Australia the wording was much different:
"The ACCC is urging consumers to respond to Mazda Australia’s 9 October 2019 voluntary safety recall of Mazda3, Mazda6 and Mazda CX-5 vehicles, as there is a serious safety issue which can result in injury or death."
"The affected Mazda vehicles have an issue with accumulation of carbon deposits in the engine’s intake shutter valve and may experience premature wear of some engine parts.
This defect can affect engine performance and cause problems with control of the vehicle. Loss of engine power and control of the vehicle, particularly in high speed situations, can lead to dangerous collisions resulting in serious injury or death."
This is why I am so concerned. Are these vehicles a ticking time bomb as the recall was never properly addressed.
Hope you are safe and well.