My 2013 RDX has approx 55k miles. The other morning after driving for 5-10 mins the "AWD Warning Light" came on and on the center dash screen showed "All-Wheel Drive: 71". AcuraLink advised if this continued to see a dealer and that the car would only operate in front wheel drive when this warning light was on. Drove another 5 mins, stopped and shut off the car and when I restarted the warning light did not come back on. Today the exact same situation happened. Has this happened to anyone else? I checked other postings and there were some posts about bad rear differentials that were replaced but nothing posted in the last several years. Looking like I'm headed to a dealership for diagnosis but would very much appreciate any insight anyone could provide. Thanks, Dean

 

Have you had the recommended fluid changes?

 

Yes I Always do whatever the service codes/dealer calls for, rear differential was changed around 17k miles, transmission and transfer fluid around 30k - I assume my next service, as I approach 60k, will call for them all to be changed and even if not recommended I planned on having them replaced at that time

 

Did you resolve this issue? I have the same issue, but seems to be temperature dependent. Comes on the same way, when it's cold out. Thanks!

 

Hello
did you resolve issue? I have same issue

 

Yes! My 2014 RDX AWD light came on everytime after driving a couple miles. I took it to Wappingers, NY Acura for a rear differential fluid change at 94K in March. They claimed they found burnt red fluid, gave me the computer code, and drove it with a laptop connected to diagnose. Said it had the wrong fluid in it and if the light came on again i'd need a $5K rear differential. It did. They never showed me the fluid, but documented in writing.
So.... I then went back to the shop that did the last rear differential fluid change at 72K, Curry Honda in Yorktown, NY. I was mad. Told them and showed them all the paperwork. They said no way they put in the wrong fluid. They looked up the code, found the Honda and then Acura service bulletins, and said it's a known problem with the rear differential sensor. Same problem with the CRV, which has the same components (pre S-AWD). A week later they gave me a loaner and replaced the sensor and fluid for $800. Lots of labor because the rear differential has to be dropped. So far, so good, 1.5K miles. The AWD light comes on and then off when I start the car so I know the sensor is working and isn't disconnected. Someone isn't being honest. Time will tell which dealership it is but for now I'm not going back to Wappingers Acura!
Car dealerships are a mess right now! Good luck!

 

I have also seen the old threads about diff replacements, sensor replacements, etc. regarding this issue, though I just wanted to remind everyone that sometimes things can sporadically appear due to weather, driving conditions, or even your battery not being healthy.

I had this same warning appear (along with various other ones) when we did a "Take your car on the track" day at Charlotte motor speedway (not spirited driving, just a tour) - all the warning lights appeared when we were on the 24 degree banked corners. They stayed on for a couple start/stops, but a simple disconnect and reconnect of the battery resolved them. That would always be my first order of business for anyone else presented with this issue for the first time.

Further, this diagram of the rear diff shows two actual sensors, one for the fluid temp and one for the fluid pressure. https://www.acuraexpressparts.com/v-...erential-mount

Did they happen to give you a part number of the sensor replaced when they did that job Otis? I'm curious which sensor is actually causing the code to be thrown, though I'd imagine it's the pressure sensor. I also just realized, I have a 2016 and I'm wondering if every vehicle in the generation had the same differential.

 

Sorry, I had the wrong part name. They kept saying sensor, but it was the rear differential solenoid assembly, Acura part # 48350-5TG-003. It's part #18 in the Acura parts diagram link you provided above.
The Acura Technical Service Bulletin is 15-012 = "AWD Light Comes On and Sets DTC C1858-73". (That's the code my 2014 RDX AWD produced.)
SYMPTOM The electric differential pressure solenoid (EDPS) has excessive oil pressure, causing the AWD indicator to come on and OTC C-1858-73 (differential fluid pressure deviation high) to set.
POSSIBLE CAUSES There is abnormal wear on the EPDS solenoid plunger.
CORRECTIVE ACTION Replace the EDPS solenoid in the rear differential.
Given my 94K miles the solenoid probably just reached it's end? This is my 3rd Acura, all purchased new (2004 MDX sold at 200K and current 2017 MDX 58Kmiles). My 2014 RDX is my 8th car (I keep them a long time) and it is BY FAR the most reliable car I have ever owned. Nothing but normal maintenance, except this item (which I'll classify as normal wear). And the V6 rocks!!! The 2017 MDX is doing well, too... so far.
Hope this clarifies and helps.

 

Thanks a TON for providing that. I am unsure how prevalent this issue is throughout the community of owners here, but that service bulletin and corresponding part number is a great reference point to have for people that may experience this issue in the future.

 

which sensor did they replace? There is only 1 temp sensor and 2 search coil assembly. A left and right

 

Sorry, they replaced the rear differential solenoid.
(see above)

 

Hey im going to order the awd module/ control unit. However for my car it shows 2 different part #s does anyone know the difference between the two. See image

1. 

 

Wow! I have been driving my 2013 RDC around with this light on for YEARS. It turns on consistently when the weather is below 75 degrees. I am not sure how much I would spend to correct it (I'm 180k miles in), but will definitely be getting a quote from my auto repair person.

 

Hello, have you looked into it yet?

This isn't just directed to you, but also anyone else who cares to share their experience: Has anybody had the AWD light and code, only to find after replacing the solenoid described in the service bulletin that it was something other than the solenoid?

Detailed history (sorry if too much detail): My 2013 RDX with 230K miles AWD light started coming on intermittently, first time in May, about 5,000 miles ago. I was out of town when it first happened and went to the Acura dealer there, who couldn't work me in, but the service advisor said it was ok to drive despite the light being on. Since then, light came on more frequently, with no rhyme nor reason. Sometimes 1x a week, others several times a day, both when moving and sitting at a red light.

Found the service bulletin thanks to the geniuses here (thank you). My hometown dealer then diagnosed it and said that's the problem, estimating over $900 to change the solenoid. Said labor is about 4 hrs. even though the bulletin says 1.4 hrs. Learned afterwards that the 1.4 hrs. is just what Acura pays its techs to fix it when covered under the service bulletin.

My dealer also suggested I could try changing the fluid first and see whether that fixed it. I did, but it didn't fix it. In fact, now with clean fluid the AWD light comes on almost continuously. The old fluid came out more the color of used transmission fluid (reddish) than the clear DPSF that went in about 35,000 miles earlier. Is that normal? Some residue was on the drain plug magnet, but didn't look alarming to my untrained eye. In retrospect, am surprised that I didn't get a maintenance minder #6 in the interim, around 30K miles. Service has always been done on time, with OEM fluids.

The dealer quote seemed a little steep, and the bulletin is pretty straightforward, so I bought the OEM Acura parts listed in the bulletin, first thinking it was a DIY job even though I only have ramps and no lift. Then, had second thoughts and went to a local independent shop who confirmed the trouble codes and agreed to install my parts, but then said with 230K miles and my driving with the light on, it could be something besides the solenoid and they couldn't be confident that it was just a bad solenoid. Fair enough. Told them I'd think about it over the weekend. A new rear diff is $thousands$.

Hence, my question. What's the likelihood that something else inside the differential is the problem, and I'll have wasted over $800? Besides gears, there's a motor and electronics in that unit. What's the forum's experience been with these rear differentials, including their longevity. I plan on at least another 100,000 miles on this well-cared for, garaged car.

Thanks, in advance!

 

I ma having same problem. 2013 RDX with 59K miles. AWD light come on randomly. when you turn off engine and trun on, light does not come on. I am wondering, if i should take it to dealer. I took it to my mechanic, but no code found on the code reader. Any advice will be appreciated. Thanks

 

Update to my 9/21/24 post above: I had the rear differential solenoid and related bolts on my '13 RDX w/230K miles replaced this week per the Acura Service Bulletin #15-012, and so far so good. AWD Light doesn't come on except just at start-up, when everything on the dash does, then immediately goes off.

Moreover, the car seems to handle better overall, and after reading and watching a few YouTubes about what Acura (Honda's) SH-AWD system does, I'm not surprised. It is all fitting together. I hadn't connected the slight degradation in performance around the time the light started coming on intermittently, especially after reading that it shouldn't damage the car. However, it's there for a reason; an integral part of the drive train's delivery of power to each wheel (back to front as well as left to right) as needed and for maximum efficiency. Happy so far, despite materials + labor over $900 installed, but worth it to me as I plan to keep this car for a long time.

Edit to add: If you're a confident DIY'er and have the equipment (lift, etc.) and probably an assistant, too, you could get all the genuine OEM Honda parts online to do the job yourself for about $200.00

 

Thanks Jim's Acura. I took it to the dealer and they told me that the whole differential tobe replace with the estimated cost of $5K. Cause of light is " DTC Differential Fluid pressure High. The dealer replace differential fluid and the drain bolt has sludge on it. The light AWD is still coming after the fluid change. Besides this, SUV is in a very good condition (Like new). This is USA car but currently in Toronto.

 

You have low mileage. Have you had regular service performed on time? Was there any noise coming from it or a performance problem?

The rear diff fluid change is maintenance minder #6, as I recall, and I believe that it comes on around every 15,000 or 30,000 miles.

It sounds to me as though the dealer wants to sell you a differential instead of performing the solenoid replacement.

I would get a second opinion, from an independent shop. And I would give them a copy of the Service Bulletin #15-012 ( .pdf file attached below) and tell them that you've heard from others who had this symptom and a new solenoid fixed it.

There is a newer replacement solenoid part number than the number on the Service Bulletin; it is: 48350-5TG-003 Solenoid Assembly. Be sure you confirm all part numbers are correct for your car. I bought the parts from an online Acura dealership, but decided to have an independent shop do the work instead of doing it myself. They did insist on doing their own diagnosis and confirmed the code, but told me that they couldn't warranty the parts that I supplied them. Fair enough. All is good.

In my case, and in every other case I've researched online, the problem causing the high pressure is the bad solenoid, as described and cured by the Service Bulletin repair.

My drain plug also had a little bit of "sludge" on it, but that's normal. The plug is magnetic in order to attract and hold metal particles from normal wear. Did yours have an unusual amount? Was the fluid slightly discolored, or burnt?

I had this job done last week, and have driven about two hundred miles since then, and the car is running perfectly. No more AWD light, improved performance and gas mileage. Definitely worth it, to me.
Good luck, and keep us posted!

 

Thank you Jim's Acura. I have not got a chance to see Transmission shop. The fluid was ok. Fluid was changed every 15K, so I am surprised. I guess I am not driving much so I should have changed fluid every year. I will update you once I take it to Shop and fixed. I hope it is safe to drive until i take it to the shop.
Thank you again

 

As far as I have been able to research, this well-known problem is with the defective rear differential solenoid, not from lack of changing the fluid annually.

The solenoid can be replaced in accordance with the Acura Service Bulletin #15-012 referenced above.

Replacing the rear differential for over $4K, if it's only a bad solenoid that would be around $700-$900 installed (or about $200 for parts if you can d.i.y.) seems like a colossal waste of money and unnecessary repair, especially on a low mileage car.

Especially when the issue and its repair seem to have been well documented.

If this isn't correct, I hope somebody will please chime in here. ymmv.