2023 Hyundai Ioniq 5 powertrain problems

The ICCU fails suddenly, typically announced by a loud pop sound from the rear of the vehicle. Once failed, the 12V battery stops charging, causing loss of all electrical power and propulsion. Vehicle enters limp mode or becomes completely immobile. Owners report this occurs without warning and recurs even after recall repairs and replacement with identical parts.

When: Throughout ownership; multiple failures reported at 20,000+ miles despite earlier repairs; no consistent mileage pattern

Symptoms owners cite: Loud pop sound from rear; Check Electrical System warning on dash; Stop Vehicle and Check Power Supply message; Complete loss of electrical power and propulsion; Vehicle enters turtle/limp mode (speed limited to 10-30 mph) before full shutdown; Vehicle will not start or restart; doors lock, shifter immobilizes; 12V battery drains to dangerously low levels

Codes mentioned: P1A9096, P1AA700

Repairs/costs cited: Dealer diagnosis confirms ICCU failure and blown fuse. Replacement ICCU and 12V battery required. Parts are on extreme backorder; repair timelines range from 1-2 weeks to 128 days. Multiple owners report dealers are replacing failed ICCUs with identical defective units.

Recalls/TSBs owners mention: Hyundai has issued two prior recalls (TSB 997, NHTSA ID 10240086; Recall 24V-868) with software updates attempting to address ICCU issues. However, these recall updates do not prevent subsequent failures. Hyundai has not redesigned or permanently fixed the root cause. Hyundai Corporate has been reported as unresponsive and dismissive when contacted about repeated failures. Affected ICCU units are on indefinite backorder.

HV battery fails to charge properly or discharges rapidly, causing sudden loss of propulsion. Battery management system displays false charge readings (e.g., shows fully charged within one minute while dashboard shows 60%). Vehicle enters turtle/limp mode and becomes immobile even with remaining charge. Error code P1B9600 indicates cell imbalance and charging/discharge failure.

When: Throughout ownership; one case at 13,652 miles; another after long highway driving (50+ miles at 70+ mph); repeats frequently with no consistent mileage trigger

Symptoms owners cite: Sudden loss of motive power on highway; Vehicle enters turtle mode (power limited) unpredictably; Inability to accelerate; vehicle slows drastically without brake lights; HV battery state of charge drops instantly from 10-15% to 0%; Battery will not charge above 47-60% capacity; Check Electrical System warnings; False/inconsistent charge readings on display

Codes mentioned: P1B9600

Repairs/costs cited: Full high-voltage battery pack replacement required. Owners report replacement timelines exceeding 30-128 days due to Hyundai manufacturing delays. One owner waited 128 days for a new battery. No estimate provided for when replacement batteries will be in stock.

Recalls/TSBs owners mention: Dealers confirm HV battery is defective and requires replacement. Hyundai has not identified root cause. Repair delays are extreme due to parts shortage. No design fix or upgraded battery version has been announced.

The rear electric oil pump (EOP) fails or overheats after extended high-speed driving, causing the rear motor to exceed safe operating temperature (>170°F) and shut down. Vehicle loses all-wheel-drive capability and defaults to front-wheel-drive only, with severe loss of power (from 325 hp dual-motor to 95 hp single front motor). Acceleration hesitation and lurching occur as front motor takes over demand. No diagnostic trouble codes are stored for EOP failure, motor temperature overheat, or zero torque output.

When: After 50-200 miles of continuous highway driving at 70+ mph, typically on warm days (70-80°F or higher); does not occur at lower speeds or temperatures

Symptoms owners cite: Lurching or hesitation during acceleration (1-3 second delay before front motor responds); Jerky acceleration that surprises driver; Sudden loss of rear motor function visible in power display (front motor doing all work); Reduced overall vehicle power and performance; Front motor indicator shows rear motor not operating; Issue resolves after vehicle cools (15+ minutes rest)

Codes mentioned: No DTC stored despite EOP Command Speed > 0 and EOP Actual Speed = 0, No DTC stored for MCU Motor Temperature overheat, No DTC stored for MCU Motor Actual Torque = 0 when commanded for higher output

Repairs/costs cited: Rear EOP replacement required. Owners report dealers initially claimed nothing is wrong or refused to repair despite diagnosis via OBD observation. At least 5 owners have experienced this issue. One owner identified replacement part cost is redacted in complaint.

Recalls/TSBs owners mention: No manufacturer recall or TSB acknowledged. Hyundai dealers have been slow at best and refused to repair at worst. No software fix available; hardware replacement (EOP) is necessary.

Vehicle loses ability to accelerate or loses all propulsion without warning while driving at highway speeds or in traffic. Vehicle may enter limp mode with severe speed reduction (from 70+ mph to 15-25 mph), lose all responsiveness to accelerator pedal, or become completely immobile. Occurs mid-drive with no prior warning lights or messages. Restarting vehicle typically restores function, but no stored error codes are found by dealers.

When: Unpredictable; occurs after 40-70+ miles of continuous driving; one case after switching lanes on freeway; another during rush-hour traffic

Symptoms owners cite: Sudden jerking or hard braking sensation followed by loss of acceleration; Vehicle slows dramatically despite accelerator input; Complete loss of responsiveness to accelerator pedal; Vehicle enters neutral gear involuntarily or is unable to shift into drive; No warning lights or messages prior to event; Smart cruise control disables with message Smart cruise conditions not met; After restart, all functions return to normal

Codes mentioned: No codes stored; dealer diagnostics show nothing wrong

Repairs/costs cited: Dealers unable to replicate or diagnose. No parts identified. Vehicle released to owner with clean diagnostics. One case resulted in drive motor replacement after extended diagnostics and consultation with design engineers (part received and installation scheduled).

Recalls/TSBs owners mention: No recalls or TSBs identified. Dealers unable to resolve due to inability to reproduce or find stored errors. One owner stated dealer ran diagnostics and found nothing.

Vehicle fails to shift from Reverse to Drive when commanded via the steering-column twisting knob control. The car does not shift gears despite the driver physically moving the selector to Drive position. Vehicle continues in Reverse or remains in a state where it does not respond to Drive command, causing the car to move backward when driver expects forward motion. No haptic or reliable feedback alerts driver that input was rejected. This occurs when car still has slight backward motion at time of shift command.

When: Occurs when vehicle has residual backward motion (even barely noticeable) at the moment Drive is selected; more likely to happen during low-speed parking/driveway maneuvers

Symptoms owners cite: Gear selector moved to Drive but vehicle remains in Reverse or does not shift; Vehicle shoots backward when driver expects forward motion; No haptic/mechanical feedback indicating shift was rejected; Visual feedback on dash is not useful during maneuver; Auditory cue is easily missed (low volume, masked by other car sounds, inaudible to hearing-impaired)

Repairs/costs cited: No repairs cited in complaints. Issue is described as design flaw in shifter logic and feedback.

Vehicle enters power-limited mode (turtle icon appears on screen) during highway driving, typically after 50-70 miles of continuous driving at highway speeds. Power output is drastically reduced, and vehicle cannot accelerate beyond very low speeds. Vehicle must be pulled over and allowed to rest 5+ minutes for power limitation to clear. This repeats if driver attempts highway speeds again shortly after. No clear relationship to battery state of charge, ambient temperature, or other easily identifiable trigger. Dealers often cannot reproduce despite Hyundai Corporate claiming they cannot reproduce without driving 60+ miles at highway speed.

When: After 50-70 miles of highway driving at 70+ mph; one case after 42 miles; recurs if highway driving is resumed too soon; one occurrence every time owner drove highway distance >50 miles over multiple trips

Symptoms owners cite: Turtle icon appears on screen; Power limited message displayed; Unable to accelerate beyond low speed (coasting required); Vehicle must coast to shoulder; Rapid deceleration without brake lights increases rear-end collision risk; Issue clears after 5+ minute rest period; No warning lights or messages prior to occurrence

Repairs/costs cited: Dealer diagnostics showed no error codes initially. One case was easily reproduced after owner was able to bring vehicle in and drive it 65+ miles (repeated failure during test drive). That dealer diagnosed and decided to replace the drive motor (part received, installation scheduled). Another owner's vehicle was at dealership undergoing on-and-off diagnosis for a couple weeks before drive motor replacement was decided.

Recalls/TSBs owners mention: Hyundai Corporate stated they could not reproduce without 60+ miles of highway driving. Dealers have had difficulty reproducing in service bay. Root cause not identified in most complaints.

Vehicle loses all electrical power without warning while in motion. All displays go dark, doors lock, shifter becomes immobilized, and vehicle becomes completely inoperable. No emergency functions or lights remain available. Vehicle may lose power on highway at high speed or in heavy traffic, creating immediate crash risk.

When: Unpredictable; one case during rush-hour traffic on bridge; another on highway in dark, snowy, high-traffic conditions; one case during freeway acceleration after busy intersection

Symptoms owners cite: Display goes completely dark; All electrical power lost; Doors lock and cannot be unlocked; Shifter immobilized; No emergency lights or functions; Vehicle slows/coasts to stop; Electrical system fault warning may appear briefly before shutdown

Repairs/costs cited: Diagnosis confirmed ICCU failure in cases where vehicle could be evaluated. Vehicle requires towing and full diagnostic.

Recalls/TSBs owners mention: No specific response documented; related to broader ICCU failure issue.

Vehicle suddenly lurches forward and accelerates without driver input or after driver has only applied brakes. Collision warning system does not alert and auto-braking does not activate. Occurs during slow, controlled parking maneuvers or when coming to a stop at intersections. Multiple similar incidents in some cases. Timing correlates with post-software-update period (26 Sep 2023 software update mentioned).

When: While slowly inching forward in parking space or coming to complete stop at intersection with foot on brake; after software update applied on 26 Sep 2023

Symptoms owners cite: Sudden forward lurch with acceleration; Occurs despite brake pedal being applied; Collision warning system fails to alert; Auto-braking does not engage; Vehicle strikes object (concrete wall, other vehicle, or nearly does so); No apparent driver input caused the acceleration

Repairs/costs cited: No repairs documented. Hyundai expressed intent to inspect vehicle after one month but had not done so yet.

Recalls/TSBs owners mention: Hyundai stated they want to inspect vehicle; no action taken within one month.

In i-Pedal (most aggressive braking energy recovery) mode, brake lights do not illuminate even though the vehicle is braking at high deceleration rates comparable to traditional brake pedal use. L1-L3 braking recovery modes show only mild deceleration and brake lights illuminate only if driver foot is fully off accelerator. This creates safety issue where following drivers cannot see brake lights and may not anticipate vehicle deceleration.

When: When using i-Pedal braking mode; brake lights only illuminate reliably in L1-L3 modes if foot is completely off accelerator

Symptoms owners cite: i-Pedal brings vehicle to complete stop but brake lights do not illuminate; No brake light feedback to following vehicles during aggressive regenerative braking; L1-L3 modes show conditional brake light behavior (only if foot off accelerator)

Repairs/costs cited: Issue may be correctable via ECU software change. Affects Hyundai and potentially Kia/Genesis (same platform).

Air conditioning system suddenly fails with loud banging noise from front passenger side, followed by complete loss of cold air output. System shuts down and does not restart. AC failure has occurred multiple times on same vehicle despite multiple dealer repair attempts. Vehicle becomes unsafe in extreme heat (Arizona temperatures cited). Dealerships have failed to properly diagnose root cause or repair issue over four visits spanning 33 days out of service.

When: Occurs without warning; same vehicle experienced repeated failures before extreme heat season began

Symptoms owners cite: Loud banging noise from front passenger area; Complete loss of air conditioning; AC stops producing cold air; Interior temperature becomes dangerously high in heat

Repairs/costs cited: Vehicle taken to Hyundai dealership four times for same issue, spending 33 days out of service. Dealership claimed vehicle was fixed at one point even though problem continued. Underlying problem was not properly diagnosed or repaired. One visit, technician demanded diagnostic fee despite vehicle being under warranty.

Recalls/TSBs owners mention: Hyundai Corporate unresponsive and dismissive. Lemon law claim was denied despite extensive repair history. Both dealership and Hyundai Corporate pressured owner to trade in vehicle without resolving defect.

Vehicle stops responding to all driver inputs while cruising on highway. Accelerator pedal, regen paddle shifters, cruise control buttons, and dashboard display all become unresponsive. Vehicle slowly loses speed as if in neutral. Functions only restore after vehicle is turned off and back on. No warning lights, messages, or auditory alerts occur during event. Timing correlates with highway congestion or high-traffic situations where loss of control is most dangerous.

When: While cruising on highway after 40+ minutes of continuous driving; occurred right after busy intersection in high-traffic scenario

Symptoms owners cite: Accelerator pedal completely unresponsive; Regen paddle shifters do not work; Cruise control buttons do not respond; Dashboard display unresponsive to touch; Vehicle slowly loses speed (acts like neutral); No warning lights or messages prior to event; Phone call may drop simultaneously; Restart restores all functions

Repairs/costs cited: Dealer diagnostics found no issues or stored errors. Battery health was in green. Vehicle was released with no repairs made.

Vehicle causes electrical overload in home charging systems. During AC Level 2 charging, home circuit breaker trips. When switched to Level 1 charger, same overload occurs and trips home circuit breaker again. This creates fire hazard for both vehicle and residence. Dealer diagnosis found failed ICCU with burnt connector pins as root cause.

When: During vehicle AC charging attempts (Level 2 and Level 1)

Symptoms owners cite: Home circuit breaker trips during charging; Repeated overload on different charger types; Burnt connector pins on ICCU detected by dealer

Repairs/costs cited: ICCU replacement required. Burnt connectors indicate potential thermal/electrical damage.

Vehicle occasionally will not start or will not allow driver to engage Drive or Reverse gear from Park. Driver must turn vehicle off and back on one to two times before car will start normally and allow gear selection. Affects vehicle reliability for daily operation.

When: Occasional; pattern not clearly defined

Symptoms owners cite: Vehicle sometimes fails to start from off/parked position; Unable to select Drive or Reverse gear on first start attempt; Multiple off/on cycles required to achieve normal operation; Requires 1-2 restart cycles before gear selection functions

Repairs/costs cited: No repairs documented in complaint.

Adaptive cruise control disables or shuts off without reason during highway driving. When manual throttle is used after shutdown, same speed variation problem occurs (rapid speed changes). Dashboard warning appears after shutdown events but no stored trouble codes are found by dealer. Warning appears 17+ times during recent 8k-mile trip but dealer cannot find any codes to address root cause.

When: During highway driving with adaptive cruise control or manual throttle; frequent dropouts over extended driving (17+ incidents in 8k miles)

Symptoms owners cite: Adaptive cruise control disables/shuts off without reason; Manual throttle shows same speed variation issue as cruise control had; Wild speed variations in cruise or manual modes; Dashboard warning appears after each dropout; No stored trouble codes found

Repairs/costs cited: Dealer unable to replicate and unable to find stored codes.