TECHNICAL SERVICE BULLETIN: EXCESSIVE OIL CONSUMPTION NU/GAMMA/THETA/KAPPA ENGINES - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area. This bulletin provides information on diagnosing and/or repairing some 2011-2024MY vehicles (refer to the table on pages 9 and 10 for applicable models and engine), which may exhibit a symptom of excessive oil consumption.
full bulletin at NHTSA ↗2021 Kia Forte engine problems
moderate Owners of the 2021 Kia Forte have filed 15 NHTSA complaints about the engine at roughly $3,100 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See engine across all vehicles →
Complaints
15
Recalls
0
Avg fix
$3,100
| Model year | engine complaints |
|---|---|
| 2017 Forte | 110 |
| 2018 Forte | 42 |
| 2019 Forte | 24 |
| 2020 Forte | 13 |
| 2021 Forte (this page) | 15 |
| 2022 Forte | 5 |
| 2024 Forte | 3 |
What stands out
Engine accounts for 22% of all owner complaints filed against this vehicle, across 6 categories tracked.
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.
TECHNICAL SERVICE BULLETIN: EXCESSIVE OIL CONSUMPTION NU/GAMMA/THETA/KAPPA ENGINES - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area. This bulletin provides information on diagnosing and/or repairing some 2011-2024MY vehicles (refer to the tables on pages 8-9 for applicable models and engine), which may exhibit a symptom of excessive oil consumption.
full bulletin at NHTSA ↗TECHNICAL SERVICE BULLETIN: LOOSE CRANKSHAFT PULLEY PARTIAL REPAIR - This bulletin provides information regarding a loose crankshaft pulley condition on certain 2020-2023MY Forte (BDm) vehicles equipped with a 1.6L T-GDI and 6-speed manual transmission, produced from May 15, 2019 through present, where excessive engine loads may cause the crankshaft pulley bolt to back out, causing the crankshaft pulley to come loose. If this condition occurs, a loose crankshaft pulley may cause the alignment dowel pin to shear and the crankshaft pulley to separate from the crankshaft.
full bulletin at NHTSA ↗TECHNICAL SERVICE BULLETIN: MAINTENANCE REMINDER FEATURE - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area.This bulletin provides information on setting the "Service Interval Reminder" feature available on most 2014-2023MY Kia vehicles (refer to model list on page 2). If the service interval reminder is set, the customer will be informed to have the next maintenance service performed, which can positively affect vehicle longevity and performance. Refer to TSB ENG241 for 2023MY~ vehicles equipped with the Oil Life Management System (OLMS) feature not included in table on page 2.
full bulletin at NHTSA ↗TECHNICAL SERVICE BULLETIN: EXCESSIVE OIL CONSUMPTION NU/GAMMA/THETA/KAPPA ENGINES - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area. This bulletin provides information on diagnosing and/or repairing some 2011-2021MY vehicles (refer to the tables on pages 8-9 for applicable models and engine), which may exhibit a symptom of excessive oil consumption.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Fifteen owners of 2021 Kia Forte report serious engine failures. The most common complaint is sudden, unexpected loss of power and stalling at highway speeds with no prior warning lights — vehicles shut down completely and either won't restart or restart with loud knocking. Several instances occur within weeks of routine oil service, suggesting service-related issues. Two owners specifically report missing or loose oil drain plugs post-service, causing complete oil starvation and catastrophic engine failure within 2,000 miles of service.
Multiple owners describe rapid oil consumption — one quart per week or less — preceding engine damage and knocking. This pattern matches Kia's acknowledged Theta II GDI engine oil-consumption defect, but several complaining owners say their VINs are excluded from recall and Kia denies coverage. Others report rod knock, lifter noise, erratic idle, and recurring check engine lights that dealers cannot reproduce or resolve.
One owner reports the entire crank pulley system detaching and falling onto a highway. Another describes engine overheating during normal traffic followed by shutdown with blown-engine diagnosis. Repair costs exceed $10,000 for engine replacement, and warranty does not cover failures after roughly 70,000 miles. Mechanics are reluctant to repair these vehicles due to Kia's known engine recalls.
Same Kia Forte engine reports on nearby years: 2018 · 2019
Failure modes owners describe
Sudden engine loss of power and stalling at highway speeds
Engine shuts down abruptly without warning while driving, particularly on highways or at higher speeds, leaving the vehicle stranded and unsafe to operate.
When: Occurs across 56,000 to 125,000 miles; many instances within weeks or months of oil service
Symptoms owners cite: Complete loss of engine power with rapid deceleration; Vehicle stalls and will not restart immediately; No warning lights or only check engine light appearing after stall; Loss of acceleration capability
Codes mentioned: P0300 (generic misfire)
Repairs/costs cited: Multiple owners report engine replacement needed; costs cited upward of $10,000 for new engine. Warranty does not cover after ~70,000 miles.
Recalls/TSBs owners mention: Kia corporate denies warranty coverage and recalls do not apply to all affected VINs despite identical failure patterns. Settlement exists for Theta II GDI engine oil consumption defect but VINs excluded from recall are denied coverage.
Excessive oil consumption leading to engine starvation
Engine burns or consumes oil rapidly, creating an oil-starvation condition that causes internal engine damage and eventual seizure.
When: 3–4 year old vehicles; consumption escalates over months
Symptoms owners cite: Consumption of one quart of oil per week or less; Engine knocking and rattling noise; Hard knock/rattle within engine compartment; Loss of power during normal driving
Repairs/costs cited: Owners report needing full engine replacement. One owner reports $10,000+ cost for new engine.
Recalls/TSBs owners mention: Kia has acknowledged in public filings that this defect (Theta II GDI engine oil consumption) poses risk of engine seizing and fire; class action settlement exists but some VINs excluded from recall coverage despite identical defect pattern.
Oil drain plug failure or absence
Oil drain plug becomes loose, falls out, or is missing after routine service, causing complete oil loss and catastrophic engine damage within miles.
When: Within 2,000–20 miles after oil service; one case at 107,000 miles post-service
Symptoms owners cite: No oil in engine detected; Sudden engine shutdown; Check engine light illumination; No prior warning signs before complete loss of oil
Repairs/costs cited: Results in catastrophic engine failure requiring full engine replacement. One case required engine replacement; photographs confirm missing drain plug with no pan damage.
Engine knocking, rod knock, and internal damage
Owners report loud knocking or rattling from engine internals suggesting worn or failed internal components such as rod bearings, pistons, or lifters.
When: At 40,000 miles and up; knocking present before complete failure or stalling
Symptoms owners cite: Loud knocking or rattling noise from engine; Rod knock sound during operation; Lifter noise; Vibration during deceleration or at idle; Eventual engine stall or failure
Repairs/costs cited: One owner reports engine replacement needed; others report mechanics reluctant to repair due to Kia engine recalls.
Recurring check engine light with vibration and loss of power
Check engine warning light illuminates repeatedly; vehicle vibrates especially during deceleration and at stops; RPMs fluctuate erratically at idle; vehicle loses power and stalls multiple times.
When: At approximately 125,000 miles; recurring across multiple start cycles
Symptoms owners cite: Check engine light illumination; Vibration while slowing or stopping; Fluctuating RPM at idle; Loss of motive power and stalling; Recurring failures despite restart
Repairs/costs cited: Dealer unable to duplicate failure; vehicle not repaired.
Crank pulley system detachment
Crank pulley system disassembles and falls off the vehicle while driving on the highway, creating a dangerous debris hazard.
When: Highway driving; mileage not specified
Symptoms owners cite: Entire crank pulley system falls out from under vehicle onto roadway
Engine overheating and shutdown
Engine overheats during normal traffic operation and shuts off after parking, leaving the vehicle inoperable and diagnosis pointing to blown engine.
When: During slow traffic progression; mileage not specified
Symptoms owners cite: Engine overheating notice on dashboard; Engine shuts down after parking; Blown engine diagnosis from dealership
Repairs/costs cited: Dealership repair ongoing; process described as lengthy.
Synthesized from 15 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 2 most recent
I am writing to report a serious safety concern involving my Kia vehicle. Shortly after getting an oil change, my car began making unusual noises and then suddenly stopped working in the middle of a busy intersection. This unexpected stall created a dangerous situation for both myself and other drivers. After having it towed to the dealership, it comes down to an engine malfunction which was not…
2021 Kia Forte VIN# [XXX] 107,000 miles While driving my Kia Forte on [XXX] i experienced a sudden noise without warning just 2 months to the exact date after an oil change. The vehicle became unsafe to operate and could not accelerate properly. In some cases it would no have it would feel like it was losing power and creating a scary and dangerous situation. A certified mechanic diagnosed…
Had engine trouble with your 2021 Kia Forte?
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 Forte?
It's a documented issue but not catastrophic. 15 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 15 complaints filed, engine issues most often appear around 109,266 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/Forte.
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.