Hey all! I'm posting here to hopefully hear from some other CX3 owners who may or may not have had the issues I'm currently encountering as the dealership is pretty useless at the moment.

The issue: On start OR while beginning to accelerate from 0km/h, the car stutters out of gear. My AT (auto-transmission) light, TMPS and TCS (traction control system) all come on and the system spits the codes U0101 and U0401. The issue is intermittent and each time I've taken it to the dealership, they've "been unable to replicate the problem" but basically every time I try to drive my car it happens without fail.

What's been done: I have checked the battery voltage while off, while cranking and while running the car and the battery seems fine. I've changed the spark plugs this month. The dealership took off the front bumper and "cleaned some connectors" but that only seems to have made the problem more frequent.

I suspect the TCM needs to be changed but the dealership doesn't want to change anything until they've come to a conclusive solution which is driving me batty.

Any help? Has anyone experienced this before?

Thanks in advance!

 

To start out the year and miles of your Mazda help and needs to be known when discussing problems ...
Because transmission related what was the last service performed specifically other then this one mentioned and at what miles?

You cannot ascertain the batterie's condition in the method you attempted you should get it properly load tested. This should be done first before anything that is power related is diagnosed!!

You information concerning the dealership and their resistance to changing that part is missing information? But again, without more information about your Mazda ??????????

The DTC you posted need much more information than just the DTC themselves. Don't take this wrong but if you are asking then you either do not have a professional grade Diagnostic scanner and or the experience level to do a proper Diagnostic service to confirm or eliminate the causes of your issues. DTC are a starting point only to do several checks not just those specifically related to the definition and description of those DTCs.

If your Mazda is still under warranty (the need for the year needed) then either return to your dealership or go to another dealership? If it is not under warranty, then find a independent service shop that has a certified Diagnostic Automotive Technician employed and that person will find your problem.

I do not recommend guessing gat the solution and then start to randomly by replacing unconfirmed problematic parts as this often creates additional issues on top of they yet unresolved ones.

 

Totally legitimate points, I am certainly not an expert, nor do I claim to be. Not having a maintenance manual certainly does not help.

To clarify, my CX3 is a 2017 GT with approx. 240,000 KMs on it. It has been in no accidents and only two owners where I am the second and I purchased it at 40,000 kms.

Last maintenance done on the vehicle was a brake pad & rotor change at 238,000 KMs approximately.

Does this clarify things enough or is there more information still missing that would be beneficial?

 

Yup helps.
You are out of warranty.

So, I recommend finding in your area an independent service shop that actually employs an Automotive Diagnostic Technician. At least if they were certified in the last 10 years they will have the necessary and basic Professional grade Diagnostic scanner and the experience to find you issue.(or ask the dealership service department if they in fact have a Mazda factory trained certified mechanic ) This is not really one that a DIY can do without either hit and miss guessing and possibly creating more issue to successfully find the problem. A better experienced Diagnostic tech should be able to fine the cause in an hour. This does not include the replacement or correction of the issue.
The other thing is you are not posting at those miles at any time was the transmission having basic service done? This could mean that if the fluid has never been changed that the servos or solenoids etc., and other electrical and mechanical parts may be failing or not working properly because of the very old fluid? This would minimum require dropping the transmission pan and looking at the condition of both the remains of old fluid on the bottom of the pan, what is collected on the pan magnet and other visual clues.
You can at least get you battery load tested. This will rule out the battery as contributing to the issue.