TECHNICAL SERVICE BULLETIN: SUBSEQUENT REPAIR ACTION: FRONT MOTOR REDUCTION GEAR ASSEMBLY REPLACEMENT (SC345Z) - This bulletin provides information regarding grinding or whining noise coming from the front motor reduction gear assembly after replacing the oil under SC345 (published in August 2025) on certain 2023-2024MY Niro EV (SG2 EV) vehicles produced from December 12, 2022 through February 7, 2024 and EV6 (CV) vehicles produced from December 14, 2022 through February 22, 2024. In rare cases, the front motor reduction gear assembly may exhibit noise after having the oil replaced.
full bulletin at NHTSA ↗2023 Kia EV6 powertrain problems
moderate 23 complaints filed with NHTSA · avg repair $2,500 · see powertrain across all vehicles →
Complaints
23
Recalls
0
Avg fix
$2,500
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.
VOLUNTARY SERVICE CAMPAIGN: OWNER NOTIFICATION (SC345) - This document is the owner notification advising that Kia is conducting a Voluntary Service Campaign to replace the gear oil in the front motor and gear reduction assembly, and fill it to the factory-specified amount in certain 2023-2024MY EV6 vehicles, manufactured from December 14, 2022 through February 22, 2024.
full bulletin at NHTSA ↗VOLUNTARY SERVICE CAMPAIGN: DEALER PRINCIPAL MEMO (SC345) - This document is the announcement to the dealer principals advising that Kia is conducting a Voluntary Service Campaign to replace the gear oil in the front motor and gear reduction assembly, and fill it to the factory-specified amount in certain 2023-2024MY EV6 vehicles, manufactured from December 14, 2022 through February 22, 2024 and Niro EV vehicles, manufactured from December 12, 2022 through February 7, 2024.
full bulletin at NHTSA ↗VOLUNTARY SERVICE CAMPAIGN: DEALER PARTS AND SERVICE MANAGER MEMO (SC345) - This document is the announcement to the dealer Parts and Service managers advising that Kia is conducting a Voluntary Service Campaign to replace the gear oil in the front motor and gear reduction assembly, and fill it to the factory-specified amount in certain 2023-2024MY EV6 vehicles, manufactured from December 14, 2022 through February 22, 2024 and Niro EV vehicles, manufactured from December 12, 2022 through February 7, 2024.
full bulletin at NHTSA ↗VOLUNTARY SERVICE CAMPAIGN: QUESTION AND ANSWER (SC345) - This document is the Question and Answer Guide containing the most frequently asked questions regarding the Voluntary Service Campaign SC.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners report the ICCU (Integrated Charging Control Unit) as the dominant failure mode. Multiple cases describe sudden total loss of propulsion while driving—at highway speeds, during parking, or after brief trips—with the vehicle either limping at 30-40 mph or shutting down completely. Many owners hear a loud pop before failure. The pattern is consistent: loss of electrical power prevents the vehicle from starting, unlocking, or responding. Dealers have performed multiple recalls (SC273A, SC302, and others) and replaced ICCUs under warranty, yet failures recur within weeks or months. One owner is now on their third ICCU replacement since November 2022. Kia and NHTSA have acknowledged the defect on the E-GMP platform, but no permanent solution has materialized.
Secondary failures include 12V auxiliary battery drain (owners report voltages stuck at 12.8V instead of charging to 14V) and charging system refusals at Level 1 and Level 2, with one incident damaging public infrastructure. One owner describes an electric oil pump that fails silently without a fault code, causing unsafe throttle lag when the rear motor disengages. Dealers frequently report "cannot reproduce" when diagnosing intermittent power loss, leaving owners stranded without resolution, loaner vehicles, or confidence the problem won't recur during their next drive.
Same Kia EV6 powertrain reports on nearby years: 2022 · 2024 · 2025
Failure modes owners describe
ICCU (Integrated Charging Control Unit) Failure
The ICCU fails, causing sudden loss of propulsion, limp mode, or complete vehicle shutdown with no power. Some owners report a loud popping sound before failure. Loss of electrical power prevents starting, unlocking, or any electrical response. Failures occur unpredictably and without warning lights in many cases. Some failures recur even after recall repairs and ICCU replacement.
When: Mileage ranges from 8,000 to 21,000 miles; failures occur during driving at various speeds (highway, 35 mph, parking situations). Some owners report multiple failures within weeks of each other.
Symptoms owners cite: Sudden loss of propulsion or complete shutdown; Limp mode with reduced speed (capped at 30-40 mph); Complete loss of electrical power (cannot start, unlock, engage gear); Loud popping sound from rear of cabin or underneath vehicle; Warning messages: 'Stop vehicle and check power supply,' 'Check electric vehicle system'; Vehicle becomes immobilized and undrivable
Repairs/costs cited: ICCU replacement under warranty. Some owners report multiple ICCU replacements (up to three replacements in one vehicle since purchase). Dealers have performed recalls SC273A and SC302, yet failures recur. One owner reports ICCU replacement on May 15, 2024, with recurrence on March 11, 2026.
Recalls/TSBs owners mention: TSB 24-EV-003H addresses this issue for Ioniq 5 but not officially for EV6, though owners report the EV6 uses the same EOP. Multiple recalls issued (SC273A, SC302, and others) but failures persist despite recall completion. NHTSA investigation opened for 2022 EV6 and 2023 Ioniq 5 on E-GMP platform. Kia has acknowledged the issue but lacks a permanent fix according to owner reports.
Electric Oil Pump (EOP) Inoperative – No Fault Code
Electric oil pump fails to operate (no RPM, torque, or DC current) when demanded, causing unsmooth ride. Rear motor stops propelling at 190–205 degrees, forcing front motor to handle all propulsion. Front-motor-only operation causes delayed throttle response and 'lag' that owner describes as unsafe. No fault code is generated to alert the driver or dealer diagnostic systems.
When: After 14 months of ownership; first manifests after 45–60 minutes of driving.
Symptoms owners cite: Rough, unsmooth ride quality; Sudden shift from rear motor to front motor propulsion; Delayed throttle response and lack of responsiveness when accelerating; 'Lag' or 'lethargic' acceleration response; Rear motor disengages at specific thermal threshold (~190–205°F)
Repairs/costs cited: Dealer confirmed EOP inspection but reported no findings. No repair completed; issue deemed 'normal' by Kia due to efficiency calculations. Owner purchased diagnostic tools to confirm EOP failure independently.
Recalls/TSBs owners mention: Kia acknowledged the problem is 'normal' operation for efficiency. TSB 24-EV-003H addresses same EOP in Ioniq 5 but EV6 not included in TSB despite using identical component. No recall issued for this condition on EV6.
12V Auxiliary Battery Failures and Charging Issues
12V auxiliary battery repeatedly dies, stranding the vehicle and preventing start-up. The charging system fails to maintain proper voltage (stays at 12.8 VDC instead of ~14V when driving). Battery becomes too depleted to allow vehicle startup on multiple occasions. One owner reports the auxiliary battery died twice within a year of purchase.
When: Occurs at various intervals; one owner experienced dead battery at 8,000 and 10,523 miles. Voltage drops observed while driving.
Symptoms owners cite: 12V battery voltage too low to start vehicle; Vehicle stranded and unable to power on; Voltage reading at 12.8 VDC while driving (below normal charging threshold); Cannot unlock doors or engage electrical systems; Charging system fails to maintain adequate voltage
Repairs/costs cited: First occurrence: dealer replaced auxiliary battery. Second occurrence (same vehicle): dealer recharged battery instead of diagnosing root cause. Towing required. Subsequent occurrences: dealership unable to reproduce the problem and unable to provide loaner vehicles while investigating.
Recalls/TSBs owners mention: No permanent fix identified. Kia customer service unable to reproduce issue. No recall or service campaign specifically addressing systemic 12V charging failure on EV6.
Charging System Failures and ICCU-Related Charging Defects
Vehicle refuses to charge via Level 1 or Level 2 charging, displaying 'Check Electrical System' warnings. Level 3 DC charging fails when Level 2 charger is connected, causing loud popping sound and immediate failure of public charging infrastructure. Vehicle enters limp mode and loss of motive power after charging-related failures. Charging errors occur intermittently, sometimes allowing only fast charge and not Level 2.
When: Errors occur during charging attempts; mileage not always specified. One incident occurred after home circuit breaker tripped.
Symptoms owners cite: 'Check Electrical System' warning during charging attempts; Loud 'pop' when connecting to Level 2 charger; Level 1 charging refused entirely; Level 2 charging failure while Level 3 initially works; 'Stop vehicle and check power supply' warning; Limp mode triggered post-charging; Loss of motive power on road after charging failure; Extended stranding (3 hours in cold weather with 3 miles range)
Repairs/costs cited: ICCU replacement performed for charging-related failures. One incident damaged public charging infrastructure. 12V battery depleted to zero within two hours of charging failure, requiring jump-start for towing.
Recalls/TSBs owners mention: ICCU recall service (SC302) performed, but charging failures recur. No comprehensive solution documented. No public notice issued regarding potential damage to charging infrastructure.
Rear Motor or Inverter Failure
Rear motor inverter or rear motor assembly fails during driving, cutting off power. One owner reports motor inverter failure with immediate power loss. Another describes rear motor ceasing propulsion and switching to front-wheel-only operation, causing unsafe delayed throttle response.
When: Approximately 8,000 miles (rear motor throttle response issue). Inverter failure during highway driving (exact mileage not stated).
Symptoms owners cite: Power cuts out suddenly; Rear motor ceases propulsion; Automatic switch to front-wheel-only operation; Delayed throttle response in front-motor-only mode; 'Check electric vehicle system' warning message
Repairs/costs cited: Inverter replacement required per dealer diagnosis. EOP inspection did not reveal issues, but root cause of motor failure not explained.
Recalls/TSBs owners mention: Case filed with manufacturer for one incident. No recall issued for motor inverter failures.
Drive Mode Unexpectedly Switches Without Driver Input
Console independently switches from rear-wheel drive to front-wheel-only propulsion mode without driver command. This occurs while driving at highway speeds (72 mph) after the accelerator is depressed. The vehicle fails to accelerate as intended when in front-wheel-only mode. Failure is intermittent and persists across multiple drive cycles.
When: Approximately 8,000 miles.
Symptoms owners cite: Drive mode switches from rear-wheel to front-wheel drive without driver input; Failure to accelerate when expected at highway speed; Intermittent failure that reoccurs persistently; Console displays independent drive mode change
Repairs/costs cited: Failure could not be duplicated by dealer. Vehicle not repaired.
Recalls/TSBs owners mention: Manufacturer made aware and a case filed, but no corrective action taken.
Synthesized from 23 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 3 most recent
I am submitting this as a supplemental statement to my existing NHTSA safety complaint regarding my electric vehicle, KIA EV6, 2023 model. Since my original filing, the vehicle has now experienced loss of power / loss of propulsion a total of three times. These incidents occur without warning, are unpredictable, and render the vehicle unsafe to operate. The vehicle can suddenly lose motive…
While driving, heard a pop and a check electric vehicle system error popped up on the dash. Car was not drivable except for very low speeds shortly after (impacted safety of the drive) until it eventually stopped being able to turn on at all.
The vehicle experienced a total power failure resulting in complete inoperability (no start, no unlock, no electrical response). This is the second occurrence within approximately five weeks. The most recent incident occurred after the vehicle was fully charged and driven the day prior. There were no warning lights or messages before the failure. The vehicle was previously inspected by an…
Had powertrain trouble with your 2023 Kia EV6?
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 2023 Kia EV6?
It's a documented issue but not catastrophic. 23 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Based on the 23 complaints filed, powertrain issues most often appear around 8,000 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/2023/Kia/EV6.
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.