TECHNICAL SERVICE BULLETIN: ITM REPLACEMENT AND ECM LOGIC IMPROVEMENT (CA2511) - This bulletin provides information to replace the Integrated Thermal Management Module (ITM) and then upgrade the Engine Control Module ‘ECM’ system software on certain K5 (DL3a) vehicles, in the event the Multifunction Indicator Lamp (MIL) is illuminated with DTC(s) P218100, P2181F0, and/or P2181F1 stored. This condition may occur due to degradation of the diaphragm inside the ITM. There are no drivability or other symptoms associated with this condition.
full bulletin at NHTSA ↗2021 Kia K5 engine problems
moderate 11 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
11
Recalls
0
Avg fix
$3,100
What stands out
Of the 4 model years of Kia K5 we track for engine problems, this one carries the most owner complaints on file — 11.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering engine 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 EMISSIONS SERVICE CAMPAIGN: OWNER NOTIFICATION (SC288) - This document is the owner notification advising that Kia is conducting a Voluntary Emissions Service Campaign on certain 2021-2024 MY K5 vehicles equipped with 1.6L Turbo Gas Direct Injection (GDI) engines to improve the logic in the Electronic Control Module (ECM) to ensure compliance with emissions regulations. Also, the subject vehicles will be inspected and, if necessary, the fuel tank and/or the Purge Control Solenoid Valve (PCSV) check valve will be replaced with a new one.
full bulletin at NHTSA ↗TECHNICAL SERVICE BULLETIN: VOLUNTARY EMISSIONS SERVICE CAMPAIGN: FUEL TANK AND/OR PCSV CHECK VALVE INSPECTION/REPLACEMENT + ECU SW UPGRADE (SC288) - This bulletin provides information to inspect the fuel evaporative system and, if necessary, replace the fuel tank and/or the Purge Control Solenoid Valve (PCSV) check valve on certain 2021-2024MY K5 (DL3a) vehicles equipped with a Gamma II 1.6L T-GDI engine, produced from March 27, 2020 through October 17, 2023. This bulletin also provides information to upgrade the ECU software logic.
full bulletin at NHTSA ↗PRODUCT IMPROVEMENT CAMPAIGN: DEALER PRINCIPAL MEMO (SC288) - This document is the announcement to the dealer principals that Kia is conducting a Voluntary Emissions Service Campaign on certain 2021-2024 MY K5 vehicles equipped with 1.6L Turbo Gas Direct Injection (GDI) engines manufactured from March 27, 2020 through October 17, 2023 to improve the logic in the Electronic Control Module (ECM) to ensure compliance with emissions regulations. Also, the subject vehicles will be inspected and, if necessary, the fuel tank and/or the Purge Control Solenoid Valve (PCSV) check valve will be replaced with a new one.
full bulletin at NHTSA ↗VOLUNTARY EMISSIONS SERVICE CAMPAIGN: DEALER PARTS AND SERVICE MANAGER MEMO (SC288) - This document is the announcement to the dealer Parts and Service Managers that Kia is conducting a Voluntary Emissions Service Campaign on certain 2021-2024 MY K5 vehicles equipped with 1.6L Turbo Gas Direct Injection (GDI) engines manufactured from March 27, 2020 through October 17, 2023 to improve the logic in the Electronic Control Module (ECM) to ensure compliance with emissions regulations. Also, the subject vehicles will be inspected and, if necessary, the fuel tank and/or the Purge Control Solenoid Valve (PCSV) check valve will be replaced with a new one.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Eleven owners describe assorted engine failures on 2021 Kia K5 models. Several experienced sudden engine shutdown while driving highway speeds—one stalled multiple times over 60 days of dealer work, then again 4 miles after pickup; another lost power at 103,000 miles (turbo failure cited). Two owners report oil leaks: one had an oil drain plug fall out 3,800 miles after an independent shop changed the oil, requiring engine replacement; another reported oil covering the engine compartment alongside recurrent valve cover failures that required nine replacement attempts.
Check engine lights appear frequently and persist post-repair. One owner had a differential pressure sensor replaced, only for the light to return the next day; diagnosis then revealed valve failure causing gas tank swelling, which both warranty and Kia refused to cover. Another owner's P0471 code persisted even after a recall check-valve replacement; the dealer identified an exhaust pressure sensor as the culprit but left it unrepaired.
Cooling system failures emerge in multiple narratives: one owner reports antifreeze leaking into the turbo and head gasket at 68,000 miles (second owner, out of warranty); another describes the radiator cap venting coolant vapors into the engine compartment. One owner's K5 displays as "on" on the dashboard but the engine won't actually crank. A dealer refused recall service on a 2023 K5, citing aftermarket parts, and both the dealership and Kia corporate declined to provide written denial documentation.
Failure modes owners describe
Check Engine Light - Differential Pressure Sensor / Valve Failure
Engine light illuminates; dealer replaced differential pressure sensor. Light returned the next day; subsequent diagnosis revealed valve failure causing gas tank swelling. Warranty and manufacturer both denied coverage—warranty cited emissions exclusion, Kia cited prior recall service campaign found no issues.
When: Unspecified mileage; check engine light came on, diagnosis and repair happened over multiple visits
Symptoms owners cite: Check engine light illumination; Engine light returned the next day after sensor repair; Car slowing down and difficult to gain speed on highway; Gas tank swelling
Codes mentioned: P0471 (or similar differential pressure/emissions code — not explicitly stated in narrative)
Repairs/costs cited: Differential pressure sensor replaced at $501.17 (warranty paid $350.28, owner paid $150.89). Valve failure and gas tank swelling were not repaired due to warranty and manufacturer denials.
Recalls/TSBs owners mention: Kia refused repair, citing prior service campaign recall that found no valve or gas tank swelling issues. Warranty company denied coverage due to emissions exclusion policy.
Oil Drain Plug Loss — Engine Seizure Risk
Oil drain plug fell out after independent shop oil change. Owner discovered oil leak at approximately 3,800 miles after the service. Dealership determined engine replacement was necessary.
When: At 78,887 miles (oil change performed at 75,085 miles; failure occurred 3,802 miles later)
Symptoms owners cite: Check engine light and low oil pressure warning light illuminated simultaneously at 60 mph; Oil visible under vehicle; Engine requiring replacement
Codes mentioned: Low oil pressure warning
Repairs/costs cited: Engine replacement required. Owner questions how loose installation could cause failure 3,800+ miles after service.
Recurrent Valve Cover Failure with Oil Leak
Valve cover failed repeatedly; replaced nine times in succession. Unknown sensor also initially diagnosed. Oil covered engine compartment. Failure recurred same day after each repair until final replacement.
When: Approximately 45,000 miles
Symptoms owners cite: Vehicle jolted forward three times and lost power at 45 mph; Check engine warning light illuminated at 60 mph; Oil all over engine compartment; Failure recurred nine times despite nine valve cover replacements
Codes mentioned: Unknown sensor code (not specified in narrative)
Repairs/costs cited: Valve cover replaced nine times. Unknown sensor replaced once. Failure pattern suggests either defective cover part, installation issue, or underlying engine problem not addressed by cover replacement alone.
Recalls/TSBs owners mention: Manufacturer was notified of the repeated failure.
Engine Stalling — Multiple Occurrences While Driving
Engine shut off abruptly multiple times while driving highway speeds, forcing driver to pull over repeatedly. Vehicle entered limp mode. Dealership worked on it for 60 days, declared repair complete, but vehicle shut off again 4 miles after pickup.
When: Unspecified mileage
Symptoms owners cite: Engine shut off while driving on highway; Engine shut off again a couple miles down the road; Vehicle entered limp mode on third start attempt; Multiple shutdowns on way to dealership; Engine shut off again 4 miles after dealership returned vehicle
Codes mentioned: Limp mode activation (specific code not stated)
Repairs/costs cited: Dealership worked on vehicle for 60 days but root cause and actual repair remain unspecified in narrative.
Check Engine Light P0471 — Exhaust Pressure Sensor Failure After Recall Repair
Vehicle was under NHTSA recall 25V794000 (Fuel System, Gasoline). Dealer replaced check valve per recall, but check engine light P0471 persisted. Subsequent diagnosis identified Exhaust Pressure Sensor causing Exhaust Gas Recirculation (EGR) sensor failure. Vehicle remained unrepaired at time of complaint.
When: Approximately 52,000 miles
Symptoms owners cite: Check engine warning light illuminated with DTC P0471
Codes mentioned: P0471
Repairs/costs cited: Check valve replaced under recall 25V794000. Exhaust Pressure Sensor and EGR sensor identified as failure root cause but repair status unknown at complaint filing.
Recalls/TSBs owners mention: NHTSA Campaign 25V794000 (Fuel System, Gasoline) — recall repair performed but did not resolve the underlying sensor issue.
Coolant System Failure — Antifreeze Into Engine / Head Gasket
Coolant leaking from cooling system, antifreeze entering turbo and head gasket. Second owner, 68,000 miles. Kia refused warranty coverage citing non-transferable 10-year / 100,000-mile warranty and owner is outside that window. Owner reports similar issue on Optima (same brand) was covered under recall.
When: At 68,000 miles (second owner, purchased used with 6,000 miles on it)
Symptoms owners cite: Antifreeze leaking through turbo; Antifreeze entering head gasket; Engine degradation requiring motor replacement
Repairs/costs cited: Motor replacement quoted. Dealership charged $200 diagnostic fee. Owner states vehicle was always maintained.
Recalls/TSBs owners mention: Kia denied warranty repair, citing non-transferable warranty status. Owner mentions similar issue on Kia Optima was covered under recall, suggesting potential pattern Kia has acknowledged.
Loss of Power / Limp Mode — Turbo Failure
Vehicle lost power while driving; turbo failure diagnosed. Owner paid $33,000 for vehicle with 35,000 miles; power loss occurred at 103,000 miles.
When: At 103,000 miles
Symptoms owners cite: Loss of power while driving; Nearly caused accident
Repairs/costs cited: Turbo failure diagnosed. Cost and repair status not specified.
Radiator Cap Venting Issue — Coolant Vapor Escape
Cooling system allows antifreeze vapors and high pressure to escape into engine area while driving and after engine shut-off. Strong coolant smell in garage when parked. Dealer verified radiator cap acts as vent allowing vapor escape.
When: Unspecified mileage
Symptoms owners cite: Antifreeze vapors and high pressure escaping into engine area while driving; Antifreeze vapors escaping after engine is parked and turned off; Strong coolant smell in garage
Repairs/costs cited: Dealer confirmed radiator cap venting behavior but repair status not specified in narrative.
Engine Does Not Start — Dashboard Shows 'On' But Engine Inactive
Vehicle displays as 'on' on dashboard but engine does not actually start. All lights and accessories illuminate, but engine remains off. Diagnostic testing shows no fault codes. Owner notes this is ongoing issue in K5 community.
When: Unspecified mileage
Symptoms owners cite: Engine does not turn on despite dashboard indicating vehicle is on; All lights and accessories illuminate normally; Diagnostics show no problems
Repairs/costs cited: No repair information provided in narrative.
Recall Service Denial — Aftermarket Parts Cited
Vehicle taken to Kia dealership for recall service. Dealership kept vehicle 6+ days, then refused service citing aftermarket parts present on vehicle. Dealership claimed vehicle was unsafe to drive. Owner requested documentation of denial; dealership refused to provide it. Kia corporate confirmed denial but also refused to provide documentation.
When: Unspecified mileage; vehicle is 2023 model year, purchased from Carmax
Symptoms owners cite: Service denial due to claimed aftermarket parts
Repairs/costs cited: Recall work not completed. No documentation provided to owner.
Recalls/TSBs owners mention: Kia corporate confirmed denial of recall service but refused to provide written documentation to owner.
Synthesized from 11 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
On Mon, Nov 18, 2025, I was driving at 60 mph with cruise on. Suddenly cruise was cancelled and check engine and low oil pressure lights came on. I pulled off road at earliest point possible. Seemed to be running ok. Drove slowly to a convenience store and turned off engine. I checked oil and it was low. When I was walking out to car after buying some oil, I saw oil under car. I called tow…
Had engine trouble with your 2021 Kia K5?
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 engine problem on the 2021 Kia K5?
It's a documented issue but not catastrophic. 11 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Based on the 11 complaints filed, engine issues most often appear around 48,500 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 $3,100 for engine 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 engine?
No active recalls currently cover engine 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/2021/Kia/K5.
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.