2016~2023 CX-9 Rear diff failure at 113k kms (70k mi)

[sm1ke]

Have u tried pulling the 30a ABS fuse, if I recall that forces all wheel drive but u also lose abs

You mean "forces FWD" right? At the moment, with the icy and snowy roads, I think it's safer for me to keep ABS working. I haven't tried pulling that fuse, but good to know regardless.

 

[Agape_365]

You mean "forces FWD" right? At the moment, with the icy and snowy roads, I think it's safer for me to keep ABS working. I haven't tried pulling that fuse, but good to know regardless.

There is also a 50amp i think it's number 16 that turns off all the sensors makes it alot more fun when playing in the snow.

 

[N7turbo]

Have u tried pulling the 30a ABS fuse, if I recall that forces all wheel drive but u also lose abs

Have you heard of anyone getting warnings on the dash after doing this? I've read that Mazda protects the PTU from overheating.

 

[Agape_365]

Have you heard of anyone getting warnings on the dash after doing this? I've read that Mazda protects the PTU from overheating.

I have only ever done it for short periods like 4 hrs.

 

[sm1ke]

Update: I haven't let this go just yet. Since late Nov I've been going back and forth with the one representative I was able to get a hold of via email. In early Dec the rep told me that Mazda Canada would not be assisting with any goodwill coverage as my vehicle was out of warranty. Despite this, I continued to make my argument that the differential failed prematurely, responding to each email politely arguing my point, despite numerous attempts from the rep to get me to give up. I would estimate that we exchanged emails maybe 2-3 times a week, excluding the holidays.

After a few requests, the representative finally agreed to forward my case to their management team for review. I got an email today saying that they will be contacting the dealership to set up an appointment where I can present my CX-9, my service logs, receipts for parts, and the differential fluid and metal chunks for inspection. I will have to pay for the diagnosis/inspection, but I'll happily pay if it means them taking my concerns seriously.

I'm really hoping this is the first step towards a rear differential replacement from Mazda, covered 100% as a goodwill repair. If they come through, they will have earned my next vehicle purchase no doubt.

Fingers crossed!!

 

[sm1ke]

Well, it looks like I've pushed this almost as far as I'm willing to go with it. Thankfully Mazda Canada has agreed to partial coverage of the repair. If I move forward with the dealership repair, they would be using brand new Mazda OEM parts, and they would be able to get my car in as early as next week, when the necessary parts come in.

The dealership advised that with Mazda Canada's contribution, I would be looking at $3050 plus taxes for the repair. I have contacted a few other reputable shops for ballpark quotes with used OEM parts, and I was being quoted at $2700 and up. I assume that these quotes could still go higher because these shops haven't even seen/inspected my car, so who knows what they might find.

I think that I may just bite the bullet on this and go with the dealership repair. At least this way I'd get new parts, a part warranty, and they're already familiar with the work that needs to be done. Just need to discuss with the wife to make sure we're on the same page. She may want to just forego the repair and live with the car the way it is now.. but she's not the one who drives it everyday so I'll be doing my best to get her on board lol.

 

[Silly Wabbit]

So what's the breakdown and how much is Mazda covering?

https://mazda.oempartsonline.com/oem-parts/mazda-differential-assembly-kat227020?c=Zz1zdXNwZW5zaW9uJnM9YXhsZS1hbmQtZGlmZmVyZW50aWFsJmw9MyZuPVNlYXJjaCBSZXN1bHRzJmE9bWF6ZGEmbz1jeC05Jnk9MjAxOCZ0PXNpZ25hdHVyZSZlPTItNWwtbDQtZ2Fz

Diff is $2k
So there is a $1k delta for tax, shipping, and labor. Not completely unreasonable considering dealership service + warranty

 

[sm1ke]

So what's the breakdown and how much is Mazda covering?

I don't have any of that yet. I've just been texting with the dealership service rep back and forth. Based on the other quotes I got though, it seems like I'm getting a pretty fair price considering the dealership is doing the work and using brand new parts. It would of course be better if I didn't have to pay for anything, but considering my situation (2 years out of powertrain warranty, no records of service from the dealership), I'll take what I can get and move past this.

The bonus too is that it sounds like they'll be able to get me in and out in about a day. I could also get this done as early as next week, but we've got family coming in for the next couple of weeks so I'll need to schedule the appt for after that.

Once I get a detailed invoice, I'll be sure to post it here.

 

[sm1ke]

Rear diff replaced. They got it done in about 6-7 hours yesterday. Here's a picture of the invoice I received. They showed me a printout of the $2650 CDN goodwill coverage that was authorized by Mazda Canada, but I didn't get a copy of that. It appears that the $2650 was discounted from the list price of the rear differential assembly, and I paid the remainder, plus labour.

 

[sm1ke]

Mazda Canada (and the manual) says that the differential fluid should only be replaced if the rear diff is submerged. However, they also say that rear diff fluid should be inspected at every service interval (every 8k km/6 months) and changed as the fluid "becomes dirty". They say that dealers inspect the rear diff fluid at each service.. but I'd bet money that they don't.

I take this to mean that the fluid is definitely not a lifetime fluid. I was advised to drain a bit of fluid to inspect at each oil change, which is annoying because I'd have to change the washers and top up the fluid every time. But there you go. According to Mazda Canada, there is no specific change interval for diff oil, but we're expected to check it periodically and replace as needed, even though the manual says nothing about inspecting the fluid.

 

[havocbringe]

Glad you got it sorted! It’s a bit frustrating how Mazda isn’t clear on when to change the fluid, but checking it regularly seems like the best approach. Even if it’s a bit of a hassle, keeping up with maintenance will help your CX-9 last. Definitely still a solid car!

 

[DustyB]

I'm posting this to vent, but also to inform.

Back in January, I noticed that the car started making loud clunking noises. They were coming from the rear and seemed to be intermittent at first, but I soon realized that I could only hear the sound when the traction control light turned on and AWD was supposed to engage. I contacted my dealership to book a diagnosis appointment, but they seemed very skeptical that this was an AWD issue and assured me that if there was an issue with the rear diff or the AWD system, I'd have a warning light on the dash (there are no warnings or lights, and no codes stored). They basically refused to schedule an appointment because they were not confident they could diagnose the intermittent noise and just wrote off my concerns about a possible rear diff failure. I contacted them a few times and also spoke with an independent mechanic, who said the same thing about codes and warning lights appearing if there was an issue with the AWD system.

In August, I did a transfer case and rear diff drain and fill myself to confirm my assumptions. The transfer case fluid looked good, but the rear diff fluid came out silver/gray, and I was able to use a pick to pull a bunch of metal chunks out of the drain hole.

I've tried to get assistance from my dealer, which I knew I wouldn't be much help as I do all my service myself and because my car's powertrain warranty lapsed in 2023. I've had issues reaching Mazda Canada via phone because both numbers that are available (Regional Office and Mazda Customer Relations) will either ring with no answer, or I'd get a message that said to call back later. It didn't seem to matter when I called, I could never get through to anyone. I finally sent my complaint through the "Contact Us" form on the website and someone eventually got back to me. I was hoping to reason with them to get some form of goodwill assistance, but it's not looking good. Bad luck I guess. They are denying that there is a manufacturer defect because if there was, I would have had issues well before the warranty expired. However, if there is no defect, and if there is no fluid change interval for the rear diff as they have posted in the manual, the differential is expected to last much longer.

The whole point of this is to let you all know that if your rear diff is failing, there is a good chance that you will not have any warning lights. This is a major safety issue as the car will behave unpredictably in low traction situations. The car thinks there is nothing wrong with the AWD system, so the traction control is less effective and the car will not "assist" when it should because it thinks AWD is active. It's basically worse than a FWD car with no traction control system now. Further, because there are no warning lights, drivers will not know that there is an issue to investigate. If I had a warning light, and if the dealership was better informed, I would have changed my rear diff fluid much earlier, and I may have been able to avoid a complete loss of AWD.

I don't know if a "late" fluid change is to blame here. When I drained the fluid into a bottle, I left it to settle, and when all the metal was at the bottom, I could see that the fluid looked just like the front transfer case's fluid. It's possible that the fluid was underfilled at the factory, as I had drained about 10oz of fluid with the metal bits included. All this to say, change your fluids. The manual doesn't specify an interval, and if you ask them, they will tell you it's a lifetime fluid - this is a lie. Change your fluid at 30k or 40k mi intervals. Save yourself the headaches I'm dealing with now.

At this point in the process, I will likely have to proceed to opening a case with CAMVAP. I just sent off one last email, so I guess we'll see. But it looks like this may be my first and last new Mazda. I can't support buying new from them if this is the kind of support I can expect. I know I'm out of warranty, but it doesn't change the fact that this component failed early and left me with an unsafe, unpredictable vehicle.

Anyone else who's had their rear diff replaced or serviced, what did it cost you? Did you go through the dealership or an independent shop?

AWD not working
Rear diff drain


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Anyone know if there's a way to force the car to operate as if it was FWD only? Right now it doesn't recognize that the AWD has failed, so the traction control doesn't step in when it needs to in low-traction situations, making it very unpredictable. As far as I can tell, there is no AWD fuse I can pull to force it into FWD only.

My 2018 was leaking at the right rear axle on diff. Dealership inspected and said the bearing was toast and a whole new diff was required. 158K Canadian unit