Transmission Gears Don't Engage When Engine/Transmission Is Warm - No Check Engine Light

AMITHKUMARG

MEMBER
2010 INFINITI FX35
3.5L
6 CYL
2WD
AUTOMATIC
166,420 MILES

I’m looking for guidance in diagnosing a transmission issue on a 2010 Infiniti FX35.

Problem:
On a cold start, the transmission engages normally. However, once the engine/transmission warms up, no gear will engage—Drive, Reverse, or any lower gears. The shifter moves correctly, but the vehicle will not move once warm.

Additional details:

- No current check engine light or active transmission codes

- I’m attaching live diagnostic data from my scan tool for reference

- Transmission fluid has already been changed

- Transmission pan was removed and cleaned, no major debris noted

What I’m trying to determine:

- Where should I begin next with diagnostics?

- Are there specific sensors, solenoids, pressure tests, or TCM-related checks I should focus on?

- Could this be a known issue (valve body, internal seal failure, torque converter, etc.)?

- Or does this behavior typically point to a full transmission replacement?

Any insight on the next diagnostic steps before committing to a transmission swap would be greatly appreciated.

Video (Click to make bigger)

Tuesday, February 3rd, 2026 AT 6:55 PM

1 Reply

STEVE W.

MECHANIC
15,510 POSTS

The description sounds like the fluid gets hot and starts bypassing the pressure control solenoid or one of the internal seals enough that it cannot generate pressure. As it works when cold it likely isn't something like clutches or apply pistons as those would normally stop one gear from applying or one would slip. Usually though that would set a code as well. Same thing would happen if it were an electronic part like a bad solenoid or circuit as those are monitored items. There are a few known issues with the valve bodies and low pressure is one of them. You might want to see if you can find another valve body and swap it as a test. Beyond that I'd look into rebuilding it if the rest of the vehicle is in good shape.

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Tuesday, February 3rd, 2026 AT 9:03 PM