2017~2024 Do I need to replace the 4mm-left rear brake pad?

At last service the dealership's technician told me the rear brake pad were left under 5mm. After that I went to another auto body shop and tried to do the replacement. However, it turned out that the rear brake of CX-5 is some kind of electric drive- citation: "they can't find the 2018 version code to release the brake. The 2017 version doesn't works and lead to all auto brake systems (SCBS, SBS, laser radar camera) malfuction ."
So here are the questions-- is that mandatory to do the replacement from a dealership? Is it necessary to replace the rear brake pads as soon as the are about 4mm thick brake?
Thanks for any helps.
 
Yes at 4mm remaining brake pad you should replace the pads and rotors.
Any auto service center or competent DIY mechanic can change these. No special tools are required.
There is a special procedure outlined in the service manual and at this link.
Maintenance Mode for 2016/2017 CX-5 electronic brakes

If the shop you visit is not aware or confident they can do this then move on to another place.
 
Yes at 4mm remaining brake pad you should replace the pads and rotors.
Any auto service center or competent DIY mechanic can change these. No special tools are required.
There is a special procedure outlined in the service manual and at this link.
Maintenance Mode for 2016/2017 CX-5 electronic brakes

If the shop you visit is not aware or confident they can do this then move on to another place.
Thank you very much for those helpful information.
 
At last service the dealership's technician told me the rear brake pad were left under 5mm. After that I went to another auto body shop and tried to do the replacement. However, it turned out that the rear brake of CX-5 is some kind of electric drive- citation: "they can't find the 2018 version code to release the brake. The 2017 version doesn't works and lead to all auto brake systems (SCBS, SBS, laser radar camera) malfuction ."
So here are the questions-- is that mandatory to do the replacement from a dealership? Is it necessary to replace the rear brake pads as soon as the are about 4mm thick brake?
Thanks for any helps.
What’s your model year and trim level? Is it a 2018 CX-5?

And how many miles does your CX-5 have? For a 2018, it seems too soon to have rear disk pads replaced unless it has something else wrong IMO.
 
What’s your model year and trim level? Is it a 2018 CX-5?

And how many miles does your CX-5 have? For a 2018, it seems too soon to have rear disk pads replaced unless it has something else wrong IMO.

It is a 2019 model CX-5 and I purchased on March 2018, approximate 30k mileage now. Local/ Highway ratio is 80/20. The auto body boss told me the brake pads could last at least a few more months, but I do feel a weak brake when comparing with the 2k miles courtesy car ( CX-5 sport) I am driving. Also I just don't want damage the disk after the brake pad worn out.
 
... And how many miles does your CX-5 have? For a 2018, it seems too soon to have rear disk pads replaced unless it has something else wrong IMO.
Good question.
It is a 2019 model CX-5 and I purchased on March 2018, approximate 30k mileage now. Local/ Highway ratio is 80/20. The auto body boss told me the brake pads could last at least a few more months, but I do feel a weak brake when comparing with the 2k miles courtesy car ( CX-5 sport) I am driving. Also I just don't want damage the disk after the brake pad worn out.
30K miles is a bit low even if most of the driving was city with more frequent use of the brakes for stop and go traffic.
Do you often use your parking brake? It is possible that it is not releasing completely so causing the early wear. When you have the service done definitely ask that brakes are inspected to confirm the rear parking brake is not sticking.
Can only speak to the facts given: 4 mm remaining rear pads
Normally that measurement is simply removing the wheel and slipping a kind of https://www.amazon.com/dp/ (commissions earned) between the rotor and outboard pad backing plate.
And, because the inboard pad is usually a bit more worn then 4 mm measured means it is definitely time to save for brake service.
No need to worry about the brake rotors - focus on good braking which will be severely impacted if the pad is worn through to the backing plate. A complete brake job will resurface or replace the rotors. And, when done by a shop they almost always replace the rotors with new. Why? Because putting new rotors on is easier, faster and more consistently results in a quality repair. Shop time = money. The equation is a bit different for a DIY repair and in some cases - like this one with so few miles on the rotors you might either pad slap if the rotors are still pretty smooth or take the rotors to a part store that offers brake resurfacing as a service.
 
It is a 2019 model CX-5 and I purchased on March 2018, approximate 30k mileage now. Local/ Highway ratio is 80/20. The auto body boss told me the brake pads could last at least a few more months, but I do feel a weak brake when comparing with the 2k miles courtesy car ( CX-5 sport) I am driving. Also I just don't want damage the disk after the brake pad worn out.
For 30K miles, your rear brake pads should be fine. You can pull the tire off and check the pad thickness by yourself, or have other reputable brake shops such as Brakes Plus® checking the rear brakes for you as a second opinion.

Electric parking brake should release itself when the car starts to move, unless you have EPB dragging issue which is another story.
 
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