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Kia G4NA Engine - Replacement Cost, Problems & CompatibilityProblems & Compatibility
The Kia G4NA is a 2.0-litre naturally aspirated petrol engine from Hyundai-Kia's Nu family, fitted to the Kia Optima, Sportage, Sorento and Hyundai i40 from 2010 to 2018. Reconditioned G4NA units are available from £1,000-£2,000 ; the engine generated 90 UK replacement requests in 2025 [EM-VERIFIED].
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Key Specs
Kia G4NA - Specifications at a Glance
Engine Code
G4NA (Nu 2.0 MPI)
Fuel
Petrol
Configuration
2.0L inline-4, naturally aspirated, DOHC, 16-valve
Power Output(s)
150-162 hp (110-119 kW); 196-205 Nm torque
Years Produced
2010-2018
UK Models Fitted
4 model families - full list in Compatibility below
2025 UK Replacement Requests
90 [EM-VERIFIED]
Replaced
G4KD (Theta II 2.0 MPI)
Replaced By
G4NC / G4FP (Smartstream 2.0 MPI / GDI)
Most Common Failure
Coil pack / ignition failure
Reconditioned Price Range
£1,000-£2,000 supply-only
Vetted UK specialists for G4NA replacements
Minimum 12-month warranty on reconditioned and rebuilt options
Fitted To
Which Kia and Hyundai Models Use the G4NA-
The G4NA is the 2.0-litre naturally aspirated member of Hyundai-Kia's Nu family of petrol engines. It was fitted primarily to mid-size saloons, SUVs and MPVs from 2010 to 2018, replacing the older Theta II G4KD in many applications.
| Model | Generation/Chassis | Badge(s) | Years | Link |
|---|---|---|---|---|
 Kia Optima | TF | 2.0 GDi / 2.0 MPI | 2011-2015 | |
| Kia Optima | JF | 2.0 GDi / 2.0 MPI | 2015-2018 | |
| Kia Sportage | QL | 2.0 GDi | 2016-2018 | |
| Kia Sorento | XM | 2.0 GDi | 2010-2015 | |
| Kia Hyundai i40 | VF | 2.0 GDi | 2011-2018 | |
| Kia Hyundai Santa Fe | DM | 2.0 GDi | 2012-2018 |
02
Kia Optima
03
Kia Sportage
04
Kia Sorento
05
Kia Hyundai i40
06
Kia Hyundai Santa Fe
CROSS-BRAND
G4NA is documented across 6 BMW applications spanning Kia Optima, Kia Sportage, Kia Sorento, Hyundai i40, Hyundai Santa Fe. Registration lookup confirms the exact suffix before quotes are sent.
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Not sure which engine your car has- Enter your registration above - we'll confirm your exact G4NA fitment before any quotes are sent.
Prices
Kia G4NA Engine Replacement Cost (UK)
Condition | Supply Only | Fitted (Independent Specialist) | Typical Warranty |
|---|
The G4NA is a simple, well-understood engine with strong parts availability. Prices vary based on whether the coil packs and plugs have been replaced, whether the GDi system (if fitted) has been serviced, and the overall condition of the donor unit. See our full reconditioned engine cost guide for context.
Labour Guide
Fitting a G4NA typically takes 7-9 hours at £65-£85/hr (independent specialist) - confirm exact labour when comparing quotes.
Price Factors
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Common Problems
Kia G4NA Engine Problems - What Actually Fails
Every engine has its weak points. Here are the known issues with the G4NA, based on real-world data and verified failure patterns.
Verified issue focus: Coil pack / ignition failure.
1. Coil pack and ignition system failure
1. Coil pack and ignition system failure
Typical onset:
60,000-100,000 miles
What happens:
Like many Hyundai-Kia petrol engines of this era, the G4NA is prone to coil pack failure. Symptoms include engine misfire, rough idle, loss of power, and the check engine light illuminating. This is the single most common issue reported on the G4NA.
Repair vs replace:
Coil packs are relatively inexpensive (around £50-£150 each) and straightforward to replace. This is a routine maintenance item, not a reason for engine replacement. Read our full ignition system failure guide
Read more about this issue
2. O2 sensor failure
2. O2 sensor failure
Typical onset:
80,000-120,000 miles
What happens:
Oxygen sensors can fail over time, leading to poor fuel economy, check engine light, and in some cases, MOT failure due to emissions issues.
Repair vs replace:
O2 sensors are replaceable (around £100-£250 each) and this is standard maintenance on higher-mileage petrol engines.
Read more about this issue
3. Oil consumption
3. Oil consumption
Typical onset:
80,000-120,000 miles
What happens:
Some G4NA engines can develop oil consumption as they age, typically due to piston ring wear or valve stem seal wear. This is more common on higher-mileage examples.
Repair vs replace:
If oil consumption is moderate (up to 1 litre per 1,000 miles), regular top-ups are the standard approach. If consumption becomes excessive, piston rings or valve stem seals may need replacement - this typically requires a rebuild.
Read more about this issue
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Engine Variants
How to Confirm You Have the G4NA
The G4NA is a specific engine code within the Hyundai-Kia Nu family of petrol engines. Unlike some families that fragment into many sub-codes with different hardware, the G4NA's variants are primarily distinguished by fuel delivery system and power output. Nu Family Overview: The Nu family includes: - G4NA - 2.0L MPI / GDi, 150-162 hp, 2.0-litre naturally aspirated petrol - G4NB - 2.0L MPI, lower-output variant fitted to some markets - G4NC - 2.0L Smartstream successor, fitted to later models - G4FD - 1.6L GDi, fitted to i30 and Cee'd Within the G4NA, the key distinctions are: - MPI (Multi-Point Injection) variant - 150 hp (110 kW), fitted to entry-level models; uses traditional port fuel injection - GDi (Gasoline Direct Injection) variant - 162 hp (119 kW), fitted to higher-spec models; uses direct injection; more prone to carbon buildup on intake valves - Market-specific tuning - Some markets received different calibration for emissions compliance How to confirm your code: 1. On the engine - the G4NA code is stamped on the engine block. Look for "G4NA" on the identification plate on the front or side of the engine. 2. On the V5C logbook - the engine number is listed; cross-reference with Hyundai-Kia parts systems. 3. VIN decode - use a Hyundai-Kia VIN decoder; the engine type will be shown. 4. Registration lookup - enter your reg above and we'll confirm the exact fitment. Similar-looking codes it is commonly confused with: - Kia G4KD - the Theta II 2.0 MPI predecessor, fitted to earlier Sportage and Optima models; similar displacement but different engine family - Kia G4LC - the 1.4-litre Kappa petrol engine, fitted to smaller models; completely different architecture - Kia G4FP - the Smartstream 1.6 T-GDi successor, fitted to newer models; turbocharged and significantly different
Why fitting the wrong revision matters: The G4NA MPI and GDi versions have different fuel systems, injectors, and engine management. A GDi engine fitted to an MPI-spec vehicle will require different fuel delivery components and ECU programming. The Smartstream G4FP (turbo) is not a direct swap at all.
Easily Confused
Kia G4KD Engine
G4KD (Theta II 2.0 MPI): - the 2.0-litre Theta II petrol that preceded the G4NA in earlier Sportage, Optima and i40 models. The G4NA (Nu) brought improved fuel economy, reduced emissions and better low-end torque.
Alternative / Next-Gen Code
Kia G4FP Engine
G4NC / G4FP (Smartstream 2.0): - the Smartstream 1.6 T-GDi and 2.0 MPI successors, fitted to newer Sportage, Optima and i40 models from 2018 onwards. They feature improved fuel injection and emissions systems.
Confirm the exact G4NA fitment
Why fitting the wrong revision matters: The G4NA MPI and GDi versions have different fuel systems, injectors, and engine management. A GDi engine fitted to an MPI-spec vehicle will require different fuel delivery components and ECU programming. The Smartstream G4FP (turbo) is not a direct swap at all.
Buying Guide
Buying a Replacement G4NA - What to Choose
Choosing the right replacement route depends on your budget, risk tolerance, and ownership goals. Here's a breakdown of your options.
Used:
** A used G4NA makes sense for lower-value Optima, Sportage or i40 examples where the car itself is worth under £3,000-£4,000. The key requirement is documented service history with the correct oil specification, and evidence that the coil packs and O2 sensors have been addressed if over 80,000 miles. The primary risk with used units is undisclosed ignition issues - insist on a diagnostic check and compression test before purchase. Used units typically cost £350-£800. View used engines
Reconditioned:
** A proper G4NA recon includes new coil packs, new spark plugs, new O2 sensors, full gasket set, and inspection of the piston rings and valve stem seals for oil consumption. This is the right call for most replacements - you get a like-new unit with the known weak points already addressed, backed by 12-24 months warranty. Reconditioned units typically cost £1,000-£2,000. View reconditioned engines
Rebuilt:
** A full rebuild is justified for higher-value examples or where the existing engine has suffered bottom-end failure or excessive oil consumption requiring new pistons and rings. An upgraded rebuild should include new piston rings, bearings, oil pump, and a full set of gaskets. For standard applications, reconditioned is usually more cost-effective. View rebuilt engines
Supply & Fit Line:
** All engines can be supplied and fitted through our network of vetted UK Kia and Hyundai specialists - nationwide coverage with 12-month warranty on labour and parts. View supply & fit
Vehicle Value Note:
** The G4NA sits in mid-range Kia and Hyundai models - Kia Optima (£3,000-£10,000), Kia Sportage (£4,000-£14,000), Hyundai i40 (£2,500-£9,000). A £1,000-£2,000 reconditioned engine plus £500-£800 fitting is a significant investment - typically 20-40% of the vehicle's value. For lower-value examples, a used engine with documented maintenance history may be more economic. For well-maintained, high-spec examples, the investment is usually justified. The G4NA's simplicity and parts availability make it a viable candidate for repair rather than scrapping in most cases.
** Compare G4NA Engine Prices Now **Correction applied:** G4NA is listed in EM_Proprietary_Data_2025.txt with 90 requests . Table A pricing from EM_Proprietary_Data_2025.txt used throughout . [No correction required - data available.] **Note:** The user prompt states "2.2L" but EM_Proprietary_Data_2025.txt lists G4NA as a 2.0L petrol engine. The 2.2L figure in the prompt appears to be incorrect based on the proprietary data. This page correctly uses 2.0L as per the source data. [Fix at source: correct user prompt to reflect G4NA is 2.0L, not 2.2L.]
Related Engines
Engines Related to the Kia G4NA
Explore engines that are closely related to the Kia G4NA, including its predecessor, successor, and key family variants.
Predecessor
Kia G4KD Engine
G4KD (Theta II 2.0 MPI): - the 2.0-litre Theta II petrol that preceded the G4NA in earlier Sportage, Optima and i40 models. The G4NA (Nu) brought improved fuel economy, reduced emissions and better low-end torque.
Successor
Kia G4FP Engine
G4NC / G4FP (Smartstream 2.0): - the Smartstream 1.6 T-GDi and 2.0 MPI successors, fitted to newer Sportage, Optima and i40 models from 2018 onwards. They feature improved fuel injection and emissions systems.
FAQ
Kia G4NAFrequently Asked Questions
Question 1How much does a Kia G4NA engine replacement cost in the UK-
A reconditioned G4NA supply-only costs around £1,000-£2,000, with fitted prices at £1,500-£2,800 including 7-9 hours of labour at independent specialist rates (£65-£85/hr). Used units start at £350 supply-only . Reconditioned units include new coil packs, spark plugs and gaskets. Prices from EM_Proprietary_Data_2025 Table A . Fitted prices include 12-month warranty on parts and labour.
- Reconditioned units include new coil packs, spark plugs and gaskets
- Prices from EM_Proprietary_Data_2025 Table A
- Fitted prices include 12-month warranty on parts and labour
Question 2What are the common problems with the Kia G4NA engine-
The G4NA's most common issues are coil pack failure (misfire, rough idle, loss of power), O2 sensor failure (check engine light, emissions issues), and oil consumption at higher mileages. The engine is generally reliable when properly maintained. Coil pack failure is the most common issue. O2 sensor replacement is standard maintenance. Regular oil changes are essential for longevity.
- Coil pack failure is the most common issue
- O2 sensor replacement is standard maintenance
- Regular oil changes are essential for longevity
Question 3Which Kia and Hyundai models use the G4NA engine-
The G4NA powered the Kia Optima (TF 2011-2015, JF 2015-2018), Kia Sportage (QL 2016-2018), Kia Sorento (XM 2010-2015), Hyundai i40 (VF 2011-2018), and Hyundai Santa Fe (DM 2012-2018). The MPI variant produces 150 hp, while the GDi variant produces 162 hp. Kia Optima and Hyundai i40 are the most common applications. GDi versions produce slightly more power. Enter your registration to confirm exact fitment.
- Kia Optima and Hyundai i40 are the most common applications
- GDi versions produce slightly more power
- Enter your registration to confirm exact fitment
Question 4Should I buy a used or reconditioned G4NA engine-
A used G4NA makes sense only with documented service history and evidence of coil pack and O2 sensor replacement if over 80,000 miles. A reconditioned unit is safer, including new coil packs, spark plugs and gaskets with 12-24 months warranty, typically costing £1,000-£2,000 supply-only. Used engines risk undisclosed ignition issues. Diagnostic check and compression test are essential. Reconditioned units address known failure points.
- Used engines risk undisclosed ignition issues
- Diagnostic check and compression test are essential
- Reconditioned units address known failure points
Question 5How do I know if my Kia or Hyundai has the G4NA engine-
The G4NA is stamped on the engine block - look for "G4NA" on the identification plate on the front or side of the engine. You can also decode your VIN using Hyundai-Kia parts systems. Enter your registration above for confirmation. The V5C logbook lists the engine number. Hyundai-Kia VIN decoders show engine type as "G4NA". MPI versions are 150 hp; GDi versions are 162 hp.
- The V5C logbook lists the engine number
- Hyundai-Kia VIN decoders show engine type as "G4NA"
- MPI versions are 150 hp; GDi versions are 162 hp
Question 6Is the G4NA a reliable engine-
Yes - the G4NA is generally considered a reliable and durable engine. With regular maintenance (oil changes using the correct specification, coil packs replaced at 80,000+ miles), G4NA engines regularly exceed 150,000 miles. The MPI version is considered more reliable than the GDi version due to the GDi's carbon buildup on intake valves. MPI version is simpler and more reliable. GDi version offers more power but needs carbon cleaning. Regular maintenance is the key to longevity.
- MPI version is simpler and more reliable
- GDi version offers more power but needs carbon cleaning
- Regular maintenance is the key to longevity
Compare Kia G4NA Engine Prices Today
Comparing G4NA engine prices on EnginesMarket is free, fast and carries no obligation. Enter your registration once and receive quotes specific to your Kia Optima, Sportage or Hyundai i40's exact engine code and fuel delivery system (MPI or GDi). Our vetted UK suppliers understand the Nu family's simple, reliable design - no guesswork, no generic quotes. With reconditioned G4NA units from around £1,000 and used units from £350, comparing takes two minutes and could save you hundreds on a quality replacement for your Kia or Hyundai's 2.0-litre petrol engine.
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Vetted UK specialists for G4NA replacements
Minimum 12-Month Warranty
Minimum 12-month warranty on reconditioned and rebuilt options
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