Ignition Coil Interchange Numbers

Verify compatibility against the original ignition coils before purchase.

Listed coil references include:

• UF651
• UF-651
• UF651T
• 5C1861
• C1804
• 1788511
• 27300-2E000
• 273002E000
• BB2651
• 48871
• C-898
• 50146
• GN10633
• 5147
• 21A0112

Spark Plug Interchange Numbers

The supplied spark-plug references include:

• 9686
• 9417
• 93175
• 94705
• 9723
• 97390
• 5356
• XP5702
• 18846-11070

Always verify both the coil and spark-plug specifications against the exact vehicle and engine before installation.

What Vehicles Fit the UF651 Coil and Spark Plug Set?

Based on the supplied fitment information, applications include the following.

Kia Soul

2012–2019 Kia Soul – compatible 1.8L/2.0L applications

The Soul represents one of the major applications for this ignition service kit.

A worn ignition system can produce:

• Rough idle
• Engine shaking
• Hesitation
• Poor acceleration
• Check Engine light
• Reduced fuel economy

Replacing worn plugs along with deteriorating coils can restore ignition performance when those components are actually responsible for the symptoms.

Kia Forte

2014–2016 Kia Forte – compatible 1.8L/2.0L applications

Important:

The supplied manufacturer fitment specifically states that this kit does NOT fit the 2017 Kia Forte.

Put that warning prominently on the product page.

A customer with parts scattered across the garage discovering that little detail halfway through installation tends to become unusually creative in the review section.

Kia Forte5

2014–2018 Kia Forte5 – compatible 1.8L/2.0L applications

Verify engine and OE numbers because powertrain configurations can differ by year and trim.

Kia Forte Koup

2014–2016 Kia Forte Koup – compatible applications

Again, confirm the engine before purchase, particularly because different Forte performance configurations may use different ignition requirements.

Kia Rondo

2014 Kia Rondo – compatible application

Verify the engine and OE coil number before ordering.

Hyundai Applications

Hyundai Elantra

2012–2016 Hyundai Elantra – compatible 1.8L/2.0L applications

The Elantra is another strong application for this four-coil/four-plug package because compatible four-cylinder engines use one coil per cylinder.

Hyundai Elantra Coupe

2013–2014 Hyundai Elantra Coupe – compatible applications

Hyundai Elantra GT

2013–2020 Hyundai Elantra GT – compatible applications

Because this range spans multiple model years and powertrain changes, OE verification is especially important on later Elantra GT applications.

Hyundai Tucson

2014–2020 Hyundai Tucson – compatible applications

Do not automatically assign the kit to every Tucson from these years. Confirm engine and original ignition-component numbers.

Why Replace Ignition Coils and Spark Plugs Together?

An ignition coil and spark plug aren’t independent systems.

They’re partners.

The coil generates the high voltage.

The spark plug gives that voltage somewhere productive to go.

As a spark plug wears, its electrodes gradually deteriorate and its effective gap can increase.

A larger gap requires more voltage to create a spark.

That means an old spark plug can place additional electrical demand on an aging ignition coil.

Replacing worn plugs while refreshing the coils therefore addresses the ignition system more completely.

Pro Street’s live How to Pick Spark Plugs for Your Build guide explains plug material, heat range, gap and why proper application matters.

Why Iridium Spark Plugs?

Iridium is commonly used in modern spark plugs because it allows a very fine center electrode while maintaining excellent durability.

For a street-driven Hyundai or Kia, the advantages can include:

• Long service life
• Consistent spark performance
• Good cold-start characteristics
• Resistance to electrode wear
• Reliable everyday operation

But the word iridium doesn’t automatically make a plug correct.

Thread diameter, reach, seat design, heat range and application must all match the engine.

That’s why exact fitment matters more than marketing language.

Symptoms of Bad Ignition Coils

Failing ignition coils can produce:

• Rough idle
• Engine shaking
• Misfires
• Hesitation
• Poor acceleration
• Loss of power
• Check Engine light
• Flashing Check Engine light
• Hard starting
• Poor fuel economy

Pro Street’s live 7 Bad Ignition Coil Symptoms You Should Never Ignore guide explains these symptoms and how to determine whether the coil is actually responsible.

What About P0300?

If your Hyundai or Kia stores:

P0300 – Random/Multiple Cylinder Misfire Detected

don’t automatically order ignition coils.

P0300 means the engine-management system has detected misfires affecting multiple cylinders or occurring randomly.

Possible causes include:

• Worn spark plugs
• Weak ignition coils
• Fuel injector problems
• Vacuum leaks
• Low fuel pressure
• Wiring problems
• Compression problems
• Engine mechanical faults

Use Pro Street’s live P0300 Random/Multiple Cylinder Misfire Causes & Fixes guide to diagnose the problem before replacing parts.

Cylinder-Specific Misfire Codes

Four-cylinder Hyundai and Kia engines can also store:

P0301 – Cylinder 1 Misfire
P0302 – Cylinder 2 Misfire
P0303 – Cylinder 3 Misfire
P0304 – Cylinder 4 Misfire

These codes tell you which cylinder is misfiring.

They don’t automatically identify the failed component.

For example, P0302 could result from:

• Cylinder-two ignition coil
• Cylinder-two spark plug
• Fuel injector
• Wiring
• Intake leak
• Low compression

Pro Street’s Most Common OBD-II Codes Explained guide provides a broader diagnostic reference for misfire and Check Engine light codes.

How to Test a Suspected UF651 Coil

If one cylinder is consistently misfiring, a coil-swap test can help.

For example, suppose you have:

P0303 – Cylinder 3 Misfire

You can:

1. Record the trouble codes and freeze-frame information.
2. Remove the cylinder-three ignition coil.
3. Move it to another cylinder.
4. Move the known-good coil into cylinder three.
5. Reassemble everything correctly.
6. Run the engine.
7. Rescan the ECU.

If the misfire moves with the coil, you’ve developed strong evidence that the coil is defective.

If P0303 stays on cylinder three, continue diagnosing.

Don’t replace four coils because cylinder three has commitment issues.

When Should Spark Plugs Be Replaced?

Spark-plug service intervals vary by vehicle, engine and plug specification.

The supplied product description suggests considering ignition service once the vehicle exceeds approximately 80,000 km, or roughly 50,000 miles, particularly when symptoms are present.

That should not replace the factory maintenance schedule.

Follow the Hyundai or Kia service interval for your exact engine.

Spark plugs should also be inspected whenever you’re diagnosing a misfire.

Look for:

• Excessive electrode wear
• Enlarged gap
• Oil contamination
• Carbon deposits
• Fuel fouling
• Cracked ceramic
• Evidence of overheating

Can New Coils and Plugs Improve Fuel Economy?

They can restore lost efficiency when the existing ignition components are worn or failing.

A misfiring cylinder doesn’t burn its air-fuel mixture efficiently.

Correcting the ignition problem can therefore restore:

• Smooth idle
• Throttle response
• Acceleration
• Fuel economy
• Starting performance

But installing new coils and plugs on a perfectly functioning engine isn’t going to transform an Elantra into an MPG perpetual-motion machine.

You’re restoring proper combustion, not violating thermodynamics.

Don’t Ignore Oil in the Spark Plug Wells

When removing the old coils, inspect each spark-plug well.

Look for:

• Engine oil
• Water
• Corrosion
• Dirt
• Carbon tracking
• Damaged connectors

Oil around the coil boot can indicate a leaking valve-cover or spark-plug-tube seal.

Installing new coils without correcting a significant oil leak can shorten the life of the replacement components.

Who Should Buy This UF651 Coil and Plug Kit?

This kit makes the most sense for owners of compatible:

• Kia Soul
• Kia Forte
• Kia Forte5
• Kia Forte Koup
• Kia Rondo
• Hyundai Elantra
• Hyundai Elantra Coupe
• Hyundai Elantra GT
• Hyundai Tucson

who want to replace all four ignition coils and all four spark plugs together.

It’s particularly attractive for a higher-mileage four-cylinder engine where both sets of original ignition components are due for inspection or replacement.

Is the UF651 Coil and 9686 Spark Plug Set Worth It?

For a compatible Hyundai or Kia four-cylinder engine, combining four UF651-style coils with four iridium spark plugs makes practical sense.

You’re refreshing the two primary ignition components at the same time rather than installing new coils over badly worn plugs.

The key is fitment.

Verify:

year + make + model + engine + coil OE number + spark-plug specification.

Once those match, the package provides a convenient complete ignition-service kit for compatible Hyundai and Kia applications.

Because replacing the entire ignition system is useful.

Replacing the entire ignition system with the wrong parts is merely cardio.