Hello, this is the first time this has happened to me. Turned my car on, went into reverse to back out of my parking space at work, and the car won't move. Pushing the pedal will rev the engine but nothing. Pushing the pedal a little harder revved the engine higher but did reverse the car back very slowly, just enough for me to shift into drive and drive out. Accelerating had no issues. Once I arrived home, I reversed the car into my parking space without issue. So it happened on a cold start but after driving about 10 minutes, it reversed like normal.
Relevant info: when driving, my shifting will skip around sometimes. Somedays the car drives perfect, other days it will slip and miss a gear shifts, especially around 50MPH.

My car has two codes P1354 and P0441. I've replaced the solenoid two times now to try and resolve P1354 but no luck. P0441 has always been there, assuming it's something with the aftermarket exhaust.
Sadly, I'm sure this is a transmission issue. I know Nothing at all about transmissions. I've owned this LS430 for 10k miles, it's currently at 119,000, and I am unsure if the transmission has been serviced. Not while I've owned it.

Can anyone advise me on what steps I should take, what to look for, etc? should I be taking it to a transmission shop or to directly to Lexus? I'm handy when it comes to small repairs but I have zero experience with anything transmission related.

I checked the dipstick and it is within the HOT operating range and the fluid is brown in color.

 

Fluid is supposed to be bright red not brown. For less than the cost to pay a shop to look at the car you can replace the transmission fluid see if things improve. Did you check the fluid with the engine running?

Those codes could be caused by a failing ECU specifically leaky capacitors, search this forum there is a wealth of info on the subject.

 

Considering the cost of a transmission replacement, I’d consider going for a diagnostic charge at Lexus or trying a reliable transmission shop for their opinion. Sounds like “ morning sickness” which can be a sign of a failing transmission. Good luck and let us know how you make out. PS. The 5 Sp trans on the first gen LS430 is generally pretty damn reliable, especially with your low miles.

 

Just got the estimate and i’m looking at $3800 in repairs.

Its not worth it. Thats a big portion of what I paid for the car less than 2yr ago. Really disappointed. Not really sure what to do next. I guess ride it until it dies and maybe get a used trans then?

Could try the ecm repair on the leaky capacitors and hope it does something but theres definitely damage to the trans

 

ECM repair is an option and all things considered relatively inexpensive.
Replace ALL the fluid with Toyota T-IV or Mobil 3309, nothing else, and see what happens.

 

I was about to give the exact same advice.... but Bradland beat me to it! Fluid change and ECM repair. Small investment to possibly save your car. Good luck.

 

thank you. is this the correct one?

 

Yes that’s the correct fluid for your transmission. You’ll need approx 11 Qts so buy 12 to factor in spillage.

 

never updated, so here it is:
at the transmission shop they had replaced the fluid as requested. no other work was done. after the transmission shop I had an alignment done (probably irrelevant), no other work has been done.
Car is shifting beautifully, still not perfect, but better than it ever has while I've owned it. it very rarely gets stuck/"skips" a gear anymore. tbh I'm not sure if it has done it at all since I left the shop.

Since the fluid replacement, I've only lost reverse once more (I started backing into every parking space as a precaution). That happened after it rained. I noticed pretty much every time after it rains my transmission acts up on a cold start, but once I continue to drive for a few minutes it goes back to running fine. any ideas why that might be?

 

Your ECU cover isn't damaged or loose to where rain might be dripping inside it? The ECU is under the hood literally right behind the driver's headlight behind the windshield washer bottle filler neck under that rectangular plastic cover at the edge of the hood, so if water was running under the hood weatherstrip then dripping onto a cracked, loose, or otherwise damaged ECU cover then maybe a drip or two of water getting into the ECU is your problem? Worth taking a look anyway.