Infiniti Q50 won't shift problems

Filed Aug 12, 2026 · Transmission · VA

While operating the vehicle, the transmission suffered an abrupt failure resulting in Diagnostic Trouble Code (DTC) P0720 (Output Speed Sensor Circuit). Further diagnostic inspection revealed a complete internal failure of the integrated valve body assembly, which houses the Transmission Control Module (TCM), solenoids, and output speed sensors. The failure caused an immediate loss of gear selection, restricting the transmission to 3rd gear ("limp mode"). Attempting to accelerate beyond 3rd gear causes violent vehicle shaking, severe hesitation, and an inability to maintain traffic speeds due to the TCM losing signal input from the speed sensors and solenoid circuits. This total valve body/TCM failure creates a critical safety hazard. Sudden restriction to 3rd gear without warning on highways or during turn movements leaves the vehicle unable to match surrounding traffic speeds, creating an immediate risk of a rear-end or side-impact collision. The vehicle has been strictly maintained according to manufacturer schedules. Because Nissan/Infiniti designed the TCM and speed sensors as an integrated unit inside the hydraulic valve body, a sensor failure requires replacing the entire valve body/TCM unit—a repair quoted at over $3,000, with complete transmission replacement exceeding that cost. This valve body/TCM failure mode is widely documented among Infiniti Q50 owners sharing the RE7R01A 7-speed automatic transmission platform, indicating a widespread electronic and mechanical defect that threatens driver safety.

Filed Jul 15, 2026 · Acceleration, Transmission · AL

While driving my 2015 Infiniti Q50s, the transmission suddenly suffered a catastrophic electronic failure, causing the vehicle to immediately drop into "limp mode." This resulted in a sudden and dangerous loss of acceleration while operating in traffic. A diagnostic scan revealed trouble codes P0500 and P0720 (Output Speed Sensor circuit). However, following Infiniti's official Technical Service Bulletin (TSB ITB19-040), the actual failure was the Transmission Control Module (TCM), which is permanently integrated into the transmission control valve body inside the transmission. Because the speed sensor cannot be replaced independently of the integrated module, I was forced to pay out-of-pocket to replace the entire transmission control valve body assembly and have a dealership program the new unit. This is a widely documented, premature failure on this vehicle platform that creates an immediate highway safety hazard when the vehicle drops power without warning.

Filed May 27, 2025 · Transmission · TX

Transmission intermittently will not shift to the next gear. Sometimes will not shift from first gear, other times will not shift from 3rd gear. Sometimes no issue at all. It is intermittent and no warning to when the issue might happened. It happens when trying to accelerate and has put me in an unsafe situation trying to accelerate on the highway or around town.

Filed Apr 1, 2025 · Engine · IL

I bought my q50 in 2020. In 2023 one of my turbo chargers began experiencing failure. This defect caused the car to drive in limp mode where it would not accelerate and caused a hazard to myself and other drivers on the road. The failure did not display any lights on my dash and I only came to know the component failed after the physical symptoms it presented and having it diagnosed by infinit. Infiniti has now issued an extended warranty for up to 120k miles on the part for owners with the defective turbos. The warranty letter also states that if owners previously replaced the part out of pocket they could seek reimbursement with proof of the repair and proof of ownership. I submitted my documents to Infiniti and they have since closed my case without reimbursement because they claim one of their associates made a mistake in beginning the claims process with me. I have attempted to continue to pursue reimbursement and Infiniti won’t return my calls. I know for certain my car and the turbo repairs qualify for this reimbursement. I believe Infiniti is attempting to work around officially recalling the cars impacted by the bad component and the warranty is being provided in its place however I also believe they are giving me such a hard time with this in hopes that I’ll just roll over and give up on the reimbursement

Filed Mar 19, 2025 · Acceleration, Transmission · LA

While driving on the interstate and coming over an overpass there was unavoidable debris located in the road. Immediately after passing over the debris there was a loud noise followed by jerking and the RPM's revved up almost like the car was in neutral. I let up off of the accelerator and then tried to accelerate again. The car would not go faster than 30mph and will not shift out of 3rd gear. I had the car towed to the dealership and the diagnostic codes reflected vehicle speed sensor and there was no physical damage that was visible under the car. I was told that the problem was in the transmission and that it would need to be changed and given an estimate that totaled over $10,000. I was also told by the service advisor that this is a known issue with the Infiniti Q50. After doing researching this a common problem and the consumer is having to pay out of pocket if the warranty has ended. This incident could have ended badly while doing 70mph on the interstate and the car just quits moving. With all of the complaints that I have read over in regards to the transmission issues yet no action has been taken to investigate this problem. It is obliviously a manufacturing issue and the consumer should not have to pay out of pocket for defective transmissions. This luxury car was not a cheap purchase. Very disappointed that with so many cases an investigation has never been done. Infiniti should be held accountable and a recall should be issued for this problem. I will not stop until I can get through to someone that can help.

Filed Feb 17, 2025 · Engine, Fuel system · MO

My car has a start and stop problem and the dealer reprogram the ecm but it didn't work got back on the road and almost got hit twice bc my car went into limp mode. And they won't fix up unless I pay even know it's a recall and my drive shaft has a recall but they said that was close out

Filed Sep 12, 2024 · Acceleration, Transmission · FL

The transmission Valve Assembly Control Module and Vehicle Speed Sensors have both failed. The car will not shift out of 2nd gear and cannot go faster than 40 mph. This is a safety issue. I had my car inspected by a certified mechanic and he diagnosed the problem. He also stated that that he has seen this a lot with Infinitis. I have maintained my car well but this is Not a maintenance issue. There are thousands of infiniti owners online stating that they had the exact same problem. I filed a case with Infiniti #52260861. This is a design flaw with All Infiniti cars and SUV's and it should be a Recall or at a minimum fixed for free by Infiniti. It cost me $3,500 to have my car fixed and this should be paid by Infiniti to me and all other Infiniti owners with this same problem.

Filed Jul 16, 2024 · Electrical, Engine · NM

Independent service center ran diagnostics and Code that pops up is the P0090. FUEL PUMP .no inspection by dealership when requested. We called dealership and they wanted to charge for inspecting vehicle. When driving vehicle stalls,in the middle of traffic. Check engine light turned on .No exaleracion when I press gas pedal. Very dangerous it stalled in the middle of traffic with children in vehicles.. the car goes to limp mode and didn't want to move . The muffler smokes and when checked the engine oil smells like gas.

Filed Jun 21, 2024 · Transmission · CA

Transmission will not shift out of 3rd gear. I was driving down the freeway in 7th gear doing 75mph when all of sudden the transmission threw itself into 2nd gear then to 3rd. It felt like I was driving over a very large boulder and my transmission was being ripped out from under the car. Then my check engine light came on. So I had it towed home. I went for a test drive and the car will shift 1st, 2nd then 3rd but won’t go to 4th. It just stays in 3rd, it doesn’t slow down, it continues to rise in rpm and speed but won’t go out of 3rd gear. It also will not go into the manual shift mode either. I have read online about thousands of others with the same exact transmission having the same exact problem. I almost was not able to control my car so it most definitely is a big safety issue. I had autozone run a scan on it and it popped up all of these codes. My dash had zero warning lights at all before the incident happened.

Filed Oct 29, 2023 · Transmission · CA

I was driving on the freeway and suddenly my vehicle would not shift into third geer causing the RPM s to go up to 4-5. As I tried to exit the car started shuddering and I was almost hit by multiple cars. I finally was able to exit and stop to park the vehicle. No warning lights came on at anytime. I had it towed to my mechanic and was told that it was the valve body control. My car only has 86k on it and I have taken exceptional care of it performing all maintenace like clockwork. Was told replacement was 8,500.00 for entire part including the housing or 4,500 and use my current housing. My mechanic checked with infinity who said they knew of this issue, but there is no recall and the part is only under warranty for 1 year.