RDX AWD Slams into DRIVE!
 

My new-to-me '18 RDX Base AWD has a problem I am just beginning to investigate.

When you drop it into 'D' it may pause a bit and the DROPS Hard into gear. There is a noticeable lurch forward.

The transmission shows zero other problems. No, shuddering. Shifts smoothly once it is in drive.

Ideas?

I recently had a similar problem during cold weather a few months ago, at approx temp of 20F, started 2018 RDX and immediately shifted in to Drive. Transmission shifted hard into gear, I drove ahead and further shifting were hard as well. I stopped, shut off motor and restarted, paused 30 seconds and the shift in to drive was smooth along with up shifts into higher gears. Start up later in same day the problem did not happen. This same issue happened a few times again on cold temperature starts and I shut off motor and restarted and hard shift issues were gone. Problem has not occurred since but I have been pre starting the vehicle and letting it warm up. I did not have this issue in warmer weather.

Purchased used in Feb 2025 from Acura dealer, they changed transmission fluid, transfer case and rear differential fluids at 94,000 km, current mileage is 112,000 km. Not sure of previous fluid changes before I purchased. I did not have this hard shift issue in winter of 2025 until December 2025 into early January, winter to date has been very cold in SW Ontario.

I'd have your mounts checked. Any idea when the fluid was changed (if ever)?

I’m doing a 3x flush now on the tranny. Does not seem to be having much of an effect.

What are there, like five or six mounts on this vehicle? Is there a particular one or two that always goes bad I wonder?

I did all of the mounts on the CRV last year and it wasn’t a big deal. This RDX looks like a stinker for access.

I'm not sure of the amount there are, but I'd imagine there's a few for the motor and transmission too.

Yeah. I ordered the front and rear engine mounts. They are electric/hydraulic and it makes a lot of sense that is where the drama lives.

Going all in. Replacing all five engine/tranny mounts. We'll see if this fixes the bang going into Drive. I know it did on a CR-V we had in the family.

It was pretty slim pickings for DIY help unless I just did not locate it in this forum.

Transmission Upper: Easy - under the air box
Transmission Lower: Easy - Take off the driver's side wheel and replace it through the wheel well
Engine Front: Mildly Challenging - get the radiator loose, hoses off, battery tray out, driver's side cooling fan out. Radiator gets bungee'd towards the bumper and the mount comes out the top between engine & core support
Engine Rear: Suck Balls Task - do this when you are adjusting your valves. It comes out the top between the engine and firewall. All work is done topside. There is room to work once the rear valve cover is off and the harness is mostly disconnected
Engine Passenger Side: Easy - do this in conjunction with the timing belt job

Here's some photos to help:
https://cimg7.ibsrv.net/gimg/acurazi...7e1ecbc6de.png
General Torque values for mounts...
https://cimg8.ibsrv.net/gimg/acurazi...f9ed130e10.jpg
Tranny Upper Mount
https://cimg9.ibsrv.net/gimg/acurazi...2483881e20.jpg
Tranny Lower Mount
https://cimg0.ibsrv.net/gimg/acurazi...d02f74f27c.jpg
Tranny Lower Mount II
https://cimg1.ibsrv.net/gimg/acurazi...18bb4c853b.jpg
Cooling Fan & Hoses Removed
https://cimg2.ibsrv.net/gimg/acurazi...9ed3d6dede.jpg
Supporting Engine
https://cimg3.ibsrv.net/gimg/acurazi...b5ff3698c7.jpg
Supporting Engine II
https://cimg4.ibsrv.net/gimg/acurazi...e22935734a.jpg
Supporting Engine III
https://cimg5.ibsrv.net/gimg/acurazi...2161eea2e3.jpg
Radiator Coaxed out of the Way
https://cimg6.ibsrv.net/gimg/acurazi...ffb5e94aac.jpg
Front Engin Mount
https://cimg7.ibsrv.net/gimg/acurazi...9d2f272a00.jpg
New Front Engine Mount
https://cimg9.ibsrv.net/gimg/acurazi...09e17b2498.jpg
Bastard Rear Engine Mount Out!
https://cimg2.ibsrv.net/gimg/acurazi...c9a2cfed02.jpg
Area for the Rear Engine Mount
https://cimg3.ibsrv.net/gimg/acurazi...7de93ffbf9.jpg
Area for the Rear Engine Mount II
https://cimg4.ibsrv.net/gimg/acurazi...2b6162bb3d.jpg
Valves adjusted. Still need to do the Timing Belt & Water Pump.
https://cimg5.ibsrv.net/gimg/acurazi...b303f07d43.jpg
Sum-b*tch OE Rear Mount at 123k Miles.

Curious if that fixes it for you.

I'm having a similar-ish issue with my first gen RDX and have an alternate theory: sticking transmission fluid pressure switches.

Two are on order from a local dealership and will hopefully be installed this weekend.

Yeah. I’ll post an update. I’m still a few days out from receiving more parts in the mail. I got caught off guard by the plastic valve covers with the replaceable tube seals. That called for a reorder from Rock Auto.

Happens to the best of us.

Motor mounts can be a challenge, big up for DIYing the job.

Clunk is reduced with new mounts, but not gone.

It only happens going into gear to Drive. Reverse you barely notice the drop into gear.

I'm stumped.

I know this might be a dumb question, but have you checked any other mounts on the car for things like the exhaust?

Not dumb in the least. I have laid up under the thing shaking what I could - things seem secure.

Maybe I will have another go at it inspecting the u-joints.

Definitely wouldn't hurt!

Have you tried replacing any of the Transmission Oil Pressure Sensors? Usually 3rd and 4th gear go out but is kind of similar symptoms to what you're describing. Hesitation and then a large clunk or bang with a forward lurch like getting rear ended.

That's what I'm planning on doing on mine. Got the parts just haven't had the time to install them yet.

Makes sense that the trans computer can't rev match with a failing pressure switch.

I believe there’s five of them for $100/ea. That’s a pricey parts cannon.

Figure out which one corresponds with the gear you are having issues with and just change that one.

I was having issues going from 2nd to 3rd... hesitation and hard shifting. I changed just that pressure switch and problem was solved.

ah, there’s the rub. There isn’t one labeled 1st gear.

Check this video out, I didn't watch all of it but in the comments someone is asking for clarification on with switches these are and the poster says it's for 1st and 2nd gear...hope this helps!

Yes, I ordered a 28610-R36-004. Thanks, I will give it a try.

The 'H' switch seems to be a mystery. Do we know what that one is for?

I found this description. The 'H' Switch is for the Torque Converter.

https://cimg8.ibsrv.net/gimg/acurazi...4e176da8bc.jpg
props to this YouTuber!

this happened on rare occasions to my wife's 2017 RDX. she'd come home and tell me about it. I'd get in the car, restart it and it never would do it for me. Finally it did it for me. Talked to my transmission expert (he rebuilt the same model 6 speed auto on my 2014 TL) and he said it sounded like an electronic/computer issue since it would run smooth most of the time. He told me to disconnect the battery for an hour to let the computer reset and relearn. He also said (and I've heard this before but thought it was a wives tale); try turning the ignition on like you were going to start your car but don't put your foot on the brake so it actually doesn't start. Then press and hold to the floor the gas pedal for about a minute. Then turn everything off, restart the car and and see what happens.

I did both these items a year and 1/2 ago and have had no problems since. Can't see motor mounts causing what you are describing, but I could be wrong.The transmission guy told me it sounded like the torque converter was attempting to lockup as soon as you put it in gear or shifted to a higher gear. Torque converter does not lock up for reverse so you won't see it there. Just telling you what he told me and it seemed to work, I'm not a transmission guy.

ATF level is good?

The transmission relearn did not have any effect. Your comment about the torque converter aligns with my thinking this is related to the 10yr/150k mile Warranty replacement of defective converters. I need to understand if the expected P0741 DTC code shows up on a simple OBD2 scanner. Or do I need to pay for a diagnostic at the dealership?

Fluid level is correct.

Luckily, these transmissions don't cost anything.
https://cimg1.ibsrv.net/gimg/acurazi...5dd4dd5b6c.png
https://cimg2.ibsrv.net/gimg/acurazi...9e2bc8f410.png

Yep they're on the very low end in terms of cost for replacements!

I'm not even especially worried about paying a premium on the tranny. It's that it has to come out with the engine from below. Not a DIY job = big $$$

These automatic transmissions are not particularly convenient to replace; therefore, it is always easier to spend 2–3 hours dropping the entire engine, transmission, and subframe assembly, and then replacing the transmission from above while the unit rests on the floor. The same approach is also the quickest way to replace the rear main seal.

Much easier to replace some fluid pressure switches than replacing the whole trans. Might be worth doing the former before resorting to the latter.

A 100% transmission replacement is the absolute last resort; after replacing the pressure switches, I would swap out the entire valve body—solenoids included—and only then condemn the torque converter.

That suggestion may amount to throwing $800 of good money after bad.

I am swapping out 3rd Pressure switch & moving the other to TC Pressure switch if that does nothing. After that, I may pay for a dealer diagnostic.

Sometimes diag is trial and error.

As another commenter mentioned, figure out which pressure switch corresponds to the harsh shift you're having and focus on that one. The OEM pressure switches for my RDX were like $75 each.

Dealer will prob just say replace the trans. They don't dive into advanced diag typically. You'd be better off with an independent Honda specialty shop, but yes be prepared to pay for diag time.

Ditto. Couldn't have said it any better myself.

I had mentioned the problem is a harsh drop into drive from neutral or park or reverse. I have a switch in hand and will do some further troubleshooting. If it was a common problem with a common solution I would have already solved it. This is more unusual.

Modern transmissions are probably more complex than the engine itself. There are very few simple and common problems.

If you're still considering a trip to the dealer, one thing you could do is write up a detailed description of your symptoms and ask them to check Techline for a potential solution or diag procedure before dropping it off.