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{{DISPLAYTITLE:Lexus RX 350 RPM Issue}}<br />
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''This conversation was exported from ChatGPT''<ref>{{cite web|title=Lexus RX 350 RPM Issue|url=https://chatgpt.com/share/69556a65-a290-8002-a217-eebca2e0b967|publisher=ChatGPT|access-date=2026-01-01}}</ref><br />
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== gpt-5-2 ==<br />
=== User: 2020 Lexus RX 350 F-Sport with over 47K miles and recently noticed that on occasions when I may need to accelerate and … ===<br />
2020 Lexus RX 350 F-Sport with over 47K miles and recently noticed that on occasions when I may need to accelerate and it will start to redline and temporarily get stuck and not drop back down to normal rpm’s .<br />
<br />
=== Assistant: That behavior on a 2020 Lexus RX 350 F-Sport 47k miles is not normal and usually points to a transmission or throttle c… ===<br />
That behavior on a 2020 Lexus RX 350 F-Sport (47k miles) is not normal and usually points to a transmission or throttle control issue, most commonly related to how the 8-speed automatic is managing shifts.<br />
<br />
Below are the most likely causes, starting with the most common for this model/year.<br />
<br />
==== Most Likely Causes ====<br />
<br />
===== 1. Transmission Hesitation / Shift Logic Issue (Very Common on RX) =====<br />
<br />
Lexus RX models (2019–2021 especially) are known for:<br />
* Delayed upshifts<br />
* RPMs climbing to redline<br />
* Transmission “holding” a gear too long before finally shifting<br />
<br />
This often happens:<br />
* During quick acceleration<br />
* When merging or passing<br />
* After slowing and re-accelerating<br />
<br />
📌 Why it happens<br />
* Transmission software struggles to decide which gear to select<br />
* The ECU thinks you still want maximum power<br />
* More noticeable in Sport or Sport+ mode<br />
<br />
✅ Fix<br />
* Lexus TSB (software update) often resolves this<br />
* Dealer reflash of the transmission control module<br />
<br />
===== 2. Throttle Position Sensor or Electronic Throttle Body Issue =====<br />
<br />
If the car:<br />
* Revves high<br />
* Doesn’t immediately respond when you lift off the gas<br />
* Feels like it’s “stuck” revving<br />
<br />
This could be:<br />
* Dirty throttle body<br />
* Faulty throttle position sensor<br />
* Accelerator pedal sensor lag<br />
<br />
✅ Fix<br />
* Throttle body cleaning<br />
* Sensor recalibration or replacement (if faulty)<br />
<br />
===== 3. Torque Converter Not Locking Properly =====<br />
<br />
A failing or slipping torque converter can cause:<br />
* RPMs to flare upward<br />
* Delayed power transfer<br />
* RPMs staying high even when speed isn’t increasing much<br />
<br />
📌 Often intermittent at first, then becomes frequent.<br />
<br />
⚠️ More serious if ignored.<br />
<br />
===== 4. Transmission Fluid Condition =====<br />
<br />
Even though Lexus markets it as “lifetime fluid”:<br />
* At ~47k miles, fluid can already degrade<br />
* Old fluid can cause erratic shifting and RPM flare<br />
<br />
✅ Fix<br />
* Drain-and-fill (NOT a flush)<br />
* Lexus Type WS fluid only<br />
<br />
===== 5. Drive Mode Effect =====<br />
<br />
In Sport / Sport+:<br />
* Transmission intentionally holds gears longer<br />
* RPMs stay higher by design<br />
<br />
📌 If this happens in Normal or Eco, it’s more concerning.<br />
<br />
==== What You Should Do Next (In Order) ====<br />
<br />
===== Step 1: Note the Conditions =====<br />
<br />
Tell the dealer:<br />
* Which drive mode (Normal / Sport / Sport+)<br />
* Happens when warm or cold<br />
* Happens during passing / merging<br />
* How long RPMs stay high<br />
<br />
===== Step 2: Ask Dealer to Check for TSB / Software Update =====<br />
<br />
Specifically request:<br />
<br />
: “Check for transmission ECU or powertrain software updates related to shift hesitation or RPM flare.”<br />
<br />
This alone fixes many RX complaints.<br />
<br />
===== Step 3: Request a Transmission Diagnostic =====<br />
<br />
Ask them to check:<br />
* Live shift data<br />
* Torque converter lock-up<br />
* Throttle input vs RPM response<br />
<br />
===== Step 4: Consider Transmission Fluid Service =====<br />
<br />
Even if Lexus says it’s lifetime, many techs recommend:<br />
* Drain & refill at 50–60k miles<br />
<br />
==== 🚨 When It’s Urgent ====<br />
<br />
Go to the dealer ASAP if you notice:<br />
* RPMs stay high even after lifting off gas<br />
* Harsh shifts afterward<br />
* Burning smell<br />
* Check engine or transmission warning<br />
<br />
==== Bottom Line ====<br />
<br />
✔ Most likely cause: transmission software or shift logic<br />
✔ Good news: often fixed with a software update<br />
⚠️ Do not ignore — prolonged RPM flare can damage the transmission<br />
<br />
If you want, tell me:<br />
* Does it happen in Normal mode?<br />
* How long do RPMs stay high (seconds)?<br />
* Any warning lights?<br />
<br />
I can narrow this down further.<br />
<br />
== References ==<br />
<references /><br />
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[[Category:ChatGPT Shares]]<br />
[[Category:openai]]</div>Lukegao