2014-2015 Q50; MIL ON WITH DTC P0720 AND MAY HAVE HARSH SHIFTING AND/OR LACK OF POWER SERVICE INFORMATION If DTC P0720 OUTPUT SPEED SENSOR is stored, follow the diagnostic procedure in the ESM. If the diagnosis leads to output speed sensor replacement, replace the control valve. Do NOT replace the output speed sensor. ï· - Refer to the ESM for control valve replacement: TRANSMISSION DRIVELINE> TRANSAXLE TRANSMISSION > 7 AT: RE7R01A > REMOVAL AND INSTALLATION > CONTROL VALVE TCM. HINT: The vehicle may also have harsh shifting and/or lack of power.
full bulletin at NHTSA ↗2014 INFINITI Q50 powertrain problems
severe Owners of the 2014 INFINITI Q50 have filed 16 NHTSA complaints about the powertrain at roughly $2,500 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See powertrain across all vehicles →
Complaints
16
Recalls
0
Avg fix
$2,500
| Model year | powertrain complaints |
|---|---|
| 2014 Q50 (this page) | 16 |
| 2015 Q50 | 35 |
| 2016 Q50 | 4 |
| 2017 Q50 | 5 |
1crash
What stands out
Among the 5 model years of INFINITI Q50 in our records for powertrain problems, this one ranks #2 by owner-complaint volume.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
TRANSMISSION & ENGINE AUTOMATED DATA COLLECTION AND DIAGNOSTIC REPORTING SERVICE INFORMATION To support proper diagnosis and to promote Fixed-Right-First-Time ? Infiniti may review CONSULT-III plus (CIII plus) data relating to vehicle operation and function to help with vehicle diagnosis and diagnostic validation. IMPORTANT: For transmission/engine repair or replacement, retailers are required to connect C-III plus and perform ?Diagnosis (All Systems)?. Performing C-III plus ?Diagnosis (All Systems)? is also required prior to contacting any Infiniti call center (i.e. TECH-LINE, PCC, or WCC) for diagnostic support or claim preauthorization. NOTE: For additional information regarding Automated
full bulletin at NHTSA ↗SERVICE INFORMATION If the glove box is removed for any reason (for example, installing an accessory kick plate, replacing an in-cabin microfilter, etc.), verify the trunk release power cancel switch operates normally after installing the glove box. See this bulletin for further detail.
full bulletin at NHTSA ↗SERVICE INFORMATION For QX60 Hybrid Vehicles, go to page 4. Q50, Q70, and M35 Hybrid Vehicles The internal combustion (IC) engine in the Q50, Q70, and M35 Hybrid vehicles is started using a high voltage motor that is integrated into the transmission. The high voltage motor gets its power from the high voltage Lithium-Ion (Li-ion) battery that is mounted between the trunk room and the rear seat. The Li-ion battery cannot be recharged using an external battery charger; therefore it is very important that the battery state of charge (SOC) is properly maintained during extended storage periods. Action must to be taken in order to prevent excessive discharge of the high voltage Li-ion battery dur
full bulletin at NHTSA ↗IF YOU CONFIRM All of the following: The FCW (Forward Collision Warning) malfunction is ON or reported to have been ON, and DTC C1A27 (ECD POWER SUPPLY CIRCUIT) is stored (Past or Current), and the brake fluid level is normal. NOTE: C1A27 is an ICC (Intelligent Cruise Control) DTC. ACTION Reprogram the ABS control unit (ABS) per the Service Procedure in this bulletin. - Part of the Service Procedure, step 20 on page 8, is a confirmation that reprogramming is needed to resolve the incident shown in Figure A and B on page 1. See this bulletin for further detail.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners of 2014 Infiniti Q50s describe two distinct transmission failure patterns. The first is a loss of upshift — transmission gets stuck in 2nd or 3rd gear, RPMs climb rapidly, and the vehicle cannot exceed 20–40 mph. Owners cite fault codes P0720 (output speed sensor), P0500 (vehicle speed sensor), and P0270 (speed output sensor), pointing to valve body and transmission control module failure. Several note the dealership has told them this is a known issue with no recall. One owner faced a replacement cost of $8,500 and another $4,500; a dealer quoted $2,400 parts and labor. A mechanic reported seeing this "a lot with Infinitis."
The second pattern involves sudden harsh downshifts or automatic gear selection — the transmission slams into a lower gear (from 7th to 2nd, or randomly into 3rd) while driving at highway speeds, causing violent deceleration, wheel lockup, shuddering, and loss of control. One owner reported a faulty chassis control module diagnosed at the dealership after the AWD vehicle pulled hard left in light snow and crashed into a guardrail; Infiniti's investigation found "no issues."
A third, separate complaint reports brake system failure where applying brakes causes unwanted forward propulsion instead of stopping, combined with low-speed driveline stutter. One owner says transmission valve body failed twice in under four years. Another reports overheating and lock failures but provides no detail.
Same INFINITI Q50 powertrain reports on nearby years: 2015
Failure modes owners describe
Transmission stuck in 2nd or 3rd gear
Transmission cannot upshift beyond 2nd or 3rd gear. Vehicle RPMs climb to 4–5k and speed is capped at 20–40 mph. No downshift occurs even when driver continues accelerating.
When: Varies; one owner at 86k miles, one at 90k miles, one at 147k miles
Symptoms owners cite: Transmission will not shift past 2nd or 3rd gear; RPMs increase to 4–5k with vehicle speed capped at 20–40 mph; Check engine light comes on (in some cases); Vehicle sputters and cannot maintain traffic flow; Manual shift mode becomes unavailable (in one case); No warning lights beforehand (in one case)
Codes mentioned: P0720, P0500, P0270
Repairs/costs cited: Valve body replacement required; costs reported range $2,400 to $8,500 depending on whether housing is reused or replaced. One owner reports transmission replacement needed. One dealership had over 700 valve bodies on backorder. One owner states this is the second replacement in the same vehicle.
Recalls/TSBs owners mention: Infiniti stated parts are only under warranty for 1 year and declined to issue a recall despite acknowledging awareness of the issue. Dealership informed owner there should be a recall but none exists. Infiniti provided no assistance in other cases.
Sudden harsh downshift or uncontrolled gear engagement
Transmission unexpectedly engages a lower gear (e.g., from 7th to 2nd, or randomly to 3rd) while driving at normal speeds, causing violent deceleration, wheel lockup, shuddering, and severe loss of vehicle control.
When: At highway speeds (40–75 mph), without warning
Symptoms owners cite: Transmission suddenly shifts down one or more gears; Violent deceleration likened to 'driving over a large boulder' or 'slamming into a low gear'; Wheels lock up, vehicle shudders; Loss of vehicle control; nearly caused accidents; Check engine light illuminates (in some cases); Loud noise from vehicle (in one case); Second occurrence in same vehicle after first transmission replacement
Codes mentioned: Check engine light (specific codes not always noted)
Repairs/costs cited: Valve body replacement or full transmission replacement required. One owner paid for full transmission replacement already; problem recurred within a few years.
Recalls/TSBs owners mention: No recall issued. Infiniti was contacted but provided no assistance in one case.
AWD chassis control module failure with unintended vehicle pull
In light snow conditions, the vehicle's front end pulls abruptly to the left without driver input, at low speeds and near-standstill. Dealership diagnostic revealed a faulty chassis control module; manufacturer inspection found no issues and declined to repair.
When: At low speed (less than 5 mph) in light snow (1–2 inches)
Symptoms owners cite: Front wheels pull vehicle hard to the left 2–3 times in bumper-to-bumper traffic; Vehicle pulled into guardrail while coasting at crawl speed, without accelerator input; No other vehicles in the area were slipping, suggesting vehicle-specific malfunction
Codes mentioned: Chassis control module fault (identified by dealership diagnostic)
Repairs/costs cited: Dealership mechanic stated the faulty chassis control module 'most definitely could have caused' the problem and recommended chassis control module repair. Infiniti's investigation refused repair; no parts replaced.
Recalls/TSBs owners mention: Infiniti sent its own mechanic, closed the investigation, stated the car had no issues, and refused to cover body damage or repairs. Vehicle was not repaired.
Brake system propels vehicle forward instead of stopping
When braking while hybrid and engine systems are attempting to manage power draw, the vehicle unexpectedly accelerates forward rather than slowing. Combined with low-speed driveline stutter during acceleration and braking below 10 mph.
When: During braking at variable speeds; stuttering occurs at speeds 10 mph and below
Symptoms owners cite: Braking causes unexpected forward propulsion instead of deceleration; Increased vehicle momentum instead of slowing; No warning lights or alerts; Low-speed stutter during acceleration from stop and during braking to stop; Difficult to navigate safe stops
Recalls/TSBs owners mention: Dealer states this is a normal operating condition.
Synthesized from 16 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 0 most recent
Had powertrain trouble with your 2014 INFINITI Q50?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the powertrain problem on the 2014 INFINITI Q50?
It's a meaningful issue. 16 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $2,500.
At what mileage does the powertrain typically fail?
Based on the 16 complaints filed, powertrain issues most often appear around 85,000 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to powertrain?
No active recalls currently cover powertrain issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2014/INFINITI/Q50.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.