2015 INFINITI Q50 Driver assistance Problems

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.

NHTSA ID

11750490

Incident

Jul 7, 2026

The transmission speed sensor has failed needs a new valve body. It seems like a very common problem with this car and it’s a $3000 fix according to my mechanic. I think there needs to be a recall issued considering everybody on this website is reporting the same problems.

NHTSA ID

11731441

Incident

Apr 14, 2026

The car just slowed down super fast on freeway almost got rear ended. It would not go past 3rd gear. Poor acceleration. Could have caused a huge accident. I got it diagnosed and they said it is valve body/speed sensor/tcm and they said this is a COMMON problem for 2015 Q50. I replaced this part 2 years ago and here we go again. Shop diagnosed and said this tcm (transmission control module which is in the transmission) but they have to change whole transmission. Everything happened all the sudden then check engine light came on.

NHTSA ID

11683201

Incident

Aug 24, 2025

i’m reporting issues with the valve body on a 2015 Q50. I have had to replace the valve body already at cost of $1700. Many others have had same issue as this is a common defect with the TMC part. This needs to be addressed as a recall.

NHTSA ID

11681660

Incident

May 1, 2025

P07200 code came up, transmission is no good because of a cheap sensor that's impossible to fix. seems to be very common and very inconvenient

NHTSA ID

11681641

Incident

Jan 23, 2025

Just over 1 week ago, I was leaving a parking lot and driving back to my home when my car wouldn't accelerate past about ~10-15 miles per hour and wasn't shifting gears. When I took my foot off the gas pedal, the gear just dropped immediately from above third to first gear and the car shook. I first noticed this when already out of the parking lot and pulling off from a median onto the road, with no engine light or other warnings. I quickly pulled into the turn lane where there wasn't traffic and turned the car off and back on. It was the same but luckily I was in eyes view of my apartment, so I drove under 10 mph and made it home. I took the vehicle to a transmission service center and the error code that came up on the computer was (P0500 - Vehicle Speed Sensor A), which the service center said is an issue with the "valve body" inside the transmission, specifically the "TCM - Transmission Control Module" that sits on top of the valve body. I contacted multiple Infiniti service centers and they all confirmed that the valve body for my vehicle (part# 31705-x133a) is back ordered by over a month and could be longer until they have it. They do not sell the Transmission Control Module separately. The valve body was quoted to me for $2200 for the part alone. I attempted to install an aftermarket valve body and a new error code came up on the computer (PO720 - Output Speed Sensor Circuit). I kept the original valve body and will hold onto it. Doing some more research, this appears to be a common issue with the Infiniti Q50 - [XXX] In addition to the reddit thread above, a quick google search for Infiniti Error codes P0500 and PO720 point to multiple sources indicating the same common experience and outcome. My vehicle has 110k miles and users in the reddit comments are also reporting the same issue with the TCM Transmission Control Module occurring between 85k - 100k miles in all cases. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11664950

Incident

May 26, 2025

Transmission, Transmission Valve body, speed sensors. After transmission shifting issues while traveling the interstate I had to have the car towed to the dealership. After the multi point inspection was performed serveral recommended itmes related to the ongoing performance and SAFETY of the vehicle listed below: Transmission $10,446.65 Transmission Valve Body $3693.92 The diagnostic code P0720. Attached is the service bulleting stating they know this will happen and when it does here's how to fix it. Yet they have never recalled the defective transmission. When I contact Infiniti consumer affairs they simply say that they cannot help me because the vehicle does not have warranty. If i had warranty then I would not be reaching out to them for assistance in replacing the transmission.

NHTSA ID

11649578

Incident

Mar 20, 2025

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.

NHTSA ID

11649291

Incident

Mar 7, 2025

P0500 vehicle speed sen/cir P0720 a/t veh speed sen/ circuit-or- output speed sensor P1574 ascd vhcl apps sensor - or lcc vhl spd sen (icc models) My safety was put at risk when the vehicle hesitated and stop changing gears while traffic was behind me. The vehicle was inspected by a local dealership which was Nissan and also Infiniti including a transmission shop named ammco. There were no warning lights that would indicate the vehicle was failing until April the 5th

NHTSA ID

11613558

Incident

Apr 5, 2024

The valve body went bad at 164k miles. Im not the only one. On all the forums and fb groups im on, there are hundreds of valv bodys going bad on the q50s for this general area of the year. On my facebook group i have seen 4 people in the past 2 days with theirs going out. Code p0720. Mine is being hauled to the shop right now so i dont have paperwork of replacement at this time for a few days

NHTSA ID

11606710

Incident

Aug 5, 2024

My car would not accelerate over 40 mph randomly after work. Once i noticed and tried to shift to a lower gear the car did not shift gears at all. When these things first happened there was no indicator lights on. The next morning the check engine light came on and the code pulled was P0720. After finding a repair shop to look further into the issue I was advised the car needed a new transmission to fix the issue. $4,000+ for the repair and as i google the issue I see that this is a common issue and it seems to always happen unexpectedly side note: also should be a recall on driver side blend door.. i almost died this summer due to cold air only blowing on one side in the middle of summer in 100• degree weather.

NHTSA ID

11548342

Incident

Sep 28, 2023

The contact owns a 2015 Infiniti Q50. The contact stated that while driving at highway speeds, the vehicle inadvertently slowed down. The vehicle failed to accelerate. The check engine warning light was illuminated. The vehicle was towed to the local dealer where it was diagnosed that a valve body replacement was needed. The vehicle was not repaired. The manufacturer was contacted, and the contact was informed that the vehicle was not covered under warranty. The failure mileage was approximately 56,000.

NHTSA ID

11524450

Incident

May 9, 2023

Mileage

56,000 mi

The speed sensor on car seems to have failed unexpectedly while driving over a bridge. The car would barely move and could have become a dangerous situation for multiple people had it been typical traffic. The issue seems to be that although the sensors are corrupted, the entire valve body or transmission must be replaced to solve the issue leaving the car inoperable. The car is currently at a repair shop. The engine light did come on shortly after. PLEASE ISSUE RECALL. https://static.nhtsa.gov/odi/tsbs/2019/MC-10168892-0001.pdf

NHTSA ID

11522300

Incident

May 12, 2023

4/16/2023 Sunday 5pm With my wife and daughter in the car, I started the vehicle in my driveway and selected Sport mode as usual. Selected reverse and backed into our turnaround then forward to the end of our driveway. Driveway is approximately 4 car lengths long with a 20 ft long apron turnaround. Almost immediately after braking at the end of the driveway while waiting for passing traffic to exit drive, vehicle suddenly accelerated and I immediately pressed the brake as hard as I could to prevent driving into passing vehicles. I could hear the tires trying to grip/spin while I was fighting to press the brake harder to hold it t back. I then panicked and selected the gear shifter to anything other than drive and it immediately did the same in reverse. After getting in into park, I immediately selected Standard mode and the vehicle performed normal afterwards. There were no warning lights or anything to indicate any issues. Previously I had noticed minor intermittent issues of high RPMs when slowing or braking while in Sport mode but it would immediately correct itself. I have not had a chance to take it for inspection as it's now Monday morning April 17. We were all very shaken. Please advise.

NHTSA ID

11517360

Incident

Apr 16, 2023

The car was being driven on a normal day and while in gear and driven the car stalled and would no longer shift automatic. The car will not come out of 3rd gear. Took the car to repair shop and was told is a known issue with this model and even the transmission or transmission valve body needs replacement. Infinite will not issue recall and I have reach out to corporate on the issue the repair want 8,000 to replace transmission the car is out of extended warranty that was purchase on the vehicle I’m only the second owner of the car well maintained and should not be having this issue of a self maintained transmission with a vehicle worth 25,000 wen brought.

NHTSA ID

11507350

Incident

Feb 6, 2023

My Car Suddenly Stopped In The Middle Of The Road With A Check Engine Light. I Have a P0720 & P0500 Codes Indicating A Vehicle Speed Sensor & Output Speed Sensor Failed While Operating . This Cause My Transmission To Fail And Not Shifting. I Am On My Way To The Dealer Now . Hopefully Infiniti Will Do The Right Thing And Fix It . At 56,000 Miles A Transmission Should Not Fail . Unexpectedly Almost Causing A Car Collision . No Prior Warning Was Provided By The Car . The Car Just Suddenly Failed . This Is A Very Serious Safety Concern .

NHTSA ID

11452378

Incident

Feb 15, 2022

When on the highway my transmission slipped then went out and wouldn’t accelerate, without any warning or sign of trouble beforehand. I scrambled to pull over and it started to accelerate again. It struggled to shift in 1st gear and second but despite going over 40 mph it would not shift to third gear. I could feel it slipping/sputtering when letting up on the accelerator and jerk when I press on the brakes. The engine will continue to rev high at lower speed. My check engine light came on and gave two codes, P0720 and P0500. I took this to my mechanic and he advised the valve body that houses the AT speed sensor be replaced and I likely need a new transmission. On a forum for Q50s another Infiniti owner said a dealer parts manager told them that Infiniti was aware there was a problem, and that the valve body was hard to come by and part of the delay was due to them redesigning the part to assure it didn't happen again. They suggested filing a case with Infiniti in case they were to issue some type of recall or TSB. He said out of the 750+ parts that were on backorder, his was #130 in line, and it still took over 2 months to receive. IF this is a known issue it is dangerous and should be addressed

NHTSA ID

11447136

Incident

Jan 6, 2022

THE AIR BAG LIGHT JUST POPPED UP ON MY DASH BOARD

NHTSA ID

11387177

Incident

Dec 3, 2020

TL* THE CONTACT OWNS A 2015 INFINITI Q50. THE CONTACT STATED WHILE DRIVING APPROXIMATELY 70 MPH, THE VEHICLE JERKED, SHIFTED GEARS, REDUCED SPEED, THE ODOMETER FLASHED, THE CHECK ENGINE WARNING LIGHT ILLUMINATED, AND THE HEATING AND AIR CONDITIONING SYSTEM WENT FROM COLD TO HOT. THE CONTACT GOT OFF THE NEAREST EXIT AND PULLED OVER AND WAITED A WHILE BEFORE CONTINUING TO DRIVE HOME TO PARK THE VEHICLE. THE CONTACT STATED THAT A DIAGNOSTIC CODE READER RETRIEVED DTC CODE: P0720 (OUTPUT SPEED SENSOR). THE CONTACT CONTACTED INFINITI OF TAMPA (4600 N DALE MABRY HWY, TAMPA, FL 33614; (813) 694-1579) AND WAS INFORMED THAT THE CAMSHAFT NEEDED TO BE REPLACED. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOT MADE AWARE OF THE ISSUE. THE APPROXIMATE FAILURE MILEAGE WAS 65,000.

NHTSA ID

11360182

Incident

Sep 15, 2020

Mileage

65,000 mi

WAS DRIVING MY INFINITI Q50 ON A NORMAL DRY DAY WHEN ALL OF A SUDDEN IT DOWN SHIFTED OR FELT LIKE I WAS DRIVING A STANDARD MODEL VS AUTOMATIC... I PULL OVER MY ENGINE LIGHT COMES ON.. I TURNED OFF ALL SENSORS ASSOCIATED WITH THE INTELLITOUCH SYSTEM THINKING IT WAS NOT JUDGING THE DISTANCE CORRECTLY BETWEEN CARS BECAUSE IT WILL AUTOMATICALLY SLOW YOUR CAR DOWN... CONTINUED DRIVING AND I'M NOTICING AS I TRY TO ACCELERATE MY CAR IS NOT SHIFTING INTO 3RD GEAR... SO I GET TO ABOUT 35-40 MPH AND NOW I CAN TELL IT'S REVVING IN THE SAME GEAR..GET HOME GOOGLE THE ISSUE AND IT SEEMS THE VALVE BODY ON THE 2015 Q50 HAS A THREAD... GO TO YOUTUBE THIS GUY HAS A VIDEO ABOUT HIM BEING TOLD IT'S THE SPEED SENSORS... BUT WHEN HE WENT FOR REPAIR INFINITI INFORMS HIM THE VALVE BODY NEEDS REPLACING. I TOOK MY CAR INTO AN INFINITI DEALER , SPENT $180 TO HAVE A DIAGNOSTIC RUN AND WAS TOLD THEIR IS A SERVICE BULLETIN FOR THE SPEED SENSORS THAT THEY SHOULD JUST REPLACE THE VALVE BODY. THE VALVE BODY IS $1635 AND ON A NATIONAL BACK ORDER AS OF AUGUST 2020 WHEN I'M EXPERIENCING THIS ISSUE.. CALLED INFINITI CONSUMER AFFAIRS AND I'M TOLD WELL UNLESS YOU PAY FOR THE PART WE CAN'T DO ANYTHING TO GET IT EXPEDITED... IT'S BEEN 45 DAYS... SO I HAVE TO TIE UP $1700 AND DON'T KNOW WHEN THIS PART MAY BE AVAILABLE.. CAN'T DRIVE CAR BECAUSE I'LL BURN MY TRANSMISSION UP... THE VALVE BODY IN 2015 Q50'S NEED TO BE RECALLED...I COULD HAVE BEEN ON THE FREEWAY OR DRIVING TO OR FROM LOUISIANA FROM HOUSTON.. LUCKILY I WAS WITHIN 15 MILES OF MY HOME.. CALLED THE OTHER 2 INFINITI DEALERS IN HOUSTON NONE OF THEM HAVE IT IN STOCK AND HAVE AT LEAST 1 Q50 WAITING FOR REPAIR.. CALLED THE DEALER IN AUSTIN ALSO NO STOCK WITH 2 VALVE BODIES ON RESERVE... I HAVE 106000 MILES ON MY Q50 AND IT'S NO LONGER UNDER WARRANTY.. THIS ISSUE HAS BEEN REPORTED AT FEWER MILES LIKE 30K-50K SO HAS NOTHING TO DO WITH THE AGE OF THE CAR.

NHTSA ID

11355542

Incident

Aug 7, 2020

Mileage

106,000 mi

ENGINE AND/OR TRANSMISSION LOST TORQUE POWER. SINCE 2016 WHILE CAR ONLY HAD 11,000 MILES ALL OF THE SUDDEN CAR LOST TORQUE POWER WHILE ACCELERATING. CHECK ENGINE INDICATOR HAS NEVER LIGHT UP AND DEALER CONSULT SCANNER HAS NEVER FOUND THE ISSUE. STILL CAR DOESNT HAVE SAME ACCELERATION NOR TORQUE WHILE GOING 0-60MPH. ALREADY I'VE SEEN SO FAR 4 CARS OF THE SAME YEAR WITH SPEED SENSOR PROBLEMS AND REPLACEMENT. MECHANICS SAY IT BEGINS BY LOOSING POWER UNTIL STOPS WORKING AND CAR WONT MOVE.

NHTSA ID

11282210

Incident

Jan 16, 2016

Mileage

11,000 mi

CARS STEERING WHEEL WILL CLUNK AND TURN OPPOSITE DIRECTIONS WILL REVERSING INTO PARKING SPOTS OR SLOWLY TAKING OFF FROM BEING STATIONARY. THIS HAS HAPPENED A FEW TIMES OVER THE COURSE OF 4 MONTHS AND I'VE ONLY HAD THE CAR FOR ABOUT 7. LAST NIGHT I WAS PULLING INTO MY DRIVEWAY AND THE STEERING WHEEL SHARPLY TURNED RIGHT, I SHIFTED THE CAR TO PARK, AND THE CAR JUST COMPLETELY DIED. NOTHING HAD WORKED AT THAT POINT, NO LIGHTS, IGNITION, KEYS, NOTHING. I GOT OUT OF THE CAR AND SHUT THE DRIVER DOOR AND EVERYTHING TURNED BACK ON EXCEPT NOW THE STEERING WHEEL WON'T TURN UNLESS USING UNREASONABLE FORCE. POWER STEERING LIGHT ILLUMINATED, CHASSIS CONTROL. THIS HAS ALSO HAPPENED ON MY TEST DRIVE WITH THE VEHICLE IN DECEMBER OF 2018 WITH 54,000 MILES BEFORE PURCHASING . THE STEERING WHEEL SLIGHTLY TWITCHED AND I EXPRESSED MY CONCERN TO THE DEALER AND HE SAID IT WAS NORMAL. IT WAS VERY LIGHTLY THAT YOU COULD HARDLY TELL IT DID IT SO I WASN'T SUSPICIOUS OF THE CAR HAVING PROBLEMS. THIS HAS NOT ALMOST CAUSED IN ACCIDENTS BUT I HAVE A 3 MONTH OLD GIRL AND THIS IS VERY UNSAFE AND ALSO MY ONLY CAR.

NHTSA ID

11258685

Incident

Sep 27, 2019

Mileage

60,000 mi

YOUR FORM DOESN'T WORK FOR ME. ALL SYSTEMS WERE AFFECTED. I TOTALED MY CAR WHILE DRIVING UP A HILL, IN CRUISE CONTROL, AND I HIT A PUDDLE. THE CAR ACCELERATED INTO THE MEDIAN. I WAS NO LONGER A DRIVER; I WAS A PASSENGER.

NHTSA ID

10903580

Incident

Aug 22, 2016

Mileage

36,000 mi

CAME TO A SLOW STOP AT A RED LIGHT IN MY 2015 INFINITI Q50. MY FOOT WAS DIRECTLY ON THE BRAKE. WITHIN SECONDS THE CAR BEGAN TO PULL FORWARD AND I APPLIED ADDITIONAL PRESSURE ON THE BRAKES BY USING BOTH FEET. THE ENGINE WAS RACING OUT OF CONTROL AND THE TIRES WERE SCREECHING. SIFTING THE GEARS DID NOT HELP. I LET OFF THE BRAKE AND TURNED RIGHT INSTEAD OF STRAIGHT IN ORDER TO AVOID HITTING CARS. SHIFTING VIOLENTLKY THE CAR FINALLY WENT BACK TO NORMAL. THE DEALER DENIES THE CAR IS AT FAULT AND SAYS THIS IS A CASE OF HUMAN ERROR.

NHTSA ID

10854384

Incident

Apr 4, 2016

Mileage

825 mi