Bad Ignition Coil Symptoms (Causes and Solutions)

Do you want to know the various bad ignition coil symptoms so as to tell when the ignition coil is bad or failing? If so, you are on the right page.

Many vehicles have an internal-combustion engine that requires electricity, air, and fuel to function. The ignition coil in modern vehicles plays a vital role in bringing the electrical part to the equation. And this means that if your ignition coil is faulty, your engine may not function properly.

Worse of all, it may stall completely. Because of these reasons, you must be able to identify the symptoms of a faulty ignition coil.

In addition, for your car’s engine to function properly, the ignition coils have to be in excellent condition. This means if the performance of your engine becomes poor, a bad ignition coil could be the reason.

This article explains the bad ignition coil symptoms, how to fix a faulty ignition coil, how much it costs, and lots more.

Read on!

Bad Ignition Coil Symptoms

Bad Ignition Coil Symptoms

Intermittent misbehavior in your car and inability to drive smoothly could suggest your vehicle’s engine coil has failed. Bad ignition coil symptoms differ based on the damage’s severity. However, the following are common signals of an ignition coil failure.

1. Backfiring

A common bad ignition coil symptom is vehicle backfiring. The early stage of a faulty engine coil can be detected by backfiring produced by your vehicle.

Backfiring occurs whenever a fuel not used in your engine combustion cylinder escapes via the exhaust outlet. If the problem is ignored, it could lead to more expensive repairs.

The backfiring issue can often be detected through black smoke emission from the exhaust outlet. You could also decipher a faulty ignition coil if you perceive gas in the smoke.

2. Poor Fuel Economy

Low fuel economy is another common bad ignition coil symptom. If your car’s mileage becomes noticeably less than how it used to be, then you could have a faulty ignition coil.

3. Engine Misfiring

Another common bad ignition coil symptom is engine misfiring. When you start such vehicles, it will lead to engine misfiring, which sounds like either a sputtering noise or a coughing sound.

You could also experience spitting and jerking when you drive at an increased speed. When idling, a car with a faulty ignition coil will exhibit signs of vibration.

4. Vehicle Stalling

A faulty ignition coil could also lead to vehicle stalling. This happens when the failed coil sends irregular sparks to your spark plugs. Your vehicle may cease totally when you stop, and you will only be left with the trouble of your vehicle’s inability to start.

5. Engine Jerking, Rough idling, Poor Power

Other bad ignition coil symptoms include hesitation while accelerating, jerking, and engine rough idle. While driving, you may feel like the car has lost some power.

6. Check Engine Light On / DTC Code

More often, an illuminated check engine light on your dashboard is a bad ignition coil symptom. Especially, engine code P0351 ( Ignition Coil – Secondary/Primary Circuit Malfunction) will display when a vehicle diagnostic tool is used for the scanning process.

The easiest method of troubleshooting a coil problem is scanning for error codes, so immediately the check engine light comes on, perform the scan with your scanning tools or visit the nearest automobile shop.

7. Engine Hard Starting

Engine hard starting is also one of the common bad ignition coil symptoms. If the coil malfunctions, the engine will crank without any sparks in the cylinder. Oftentimes, it dies off immediately after it starts.

Also Read: Ignition Coil Packs (Everything to Know)

What Do Ignition Coils Do?

Bad Ignition Coil Symptoms

Your car’s engine requires the correct mixture of oxygen and gasoline to generate power. Also, a spark to kindle the mixture will be needed. A vehicle battery has only 12volts.

This is nothing compared to the thousands of volts required to ignite the appropriate kind of spark.

The ignition coil transforms your battery’s voltage to the degree that enables the spark plug to perform its function.

You can find spark plug wires, ignition coil, and a distributor in older cars. Many cars manufactured after the late 90s commonly have a little ignition coil placed directly on each spark plug top, referred to as a coil-on-plug (COP) pattern.

However, its functionality remains the same. The current goes into the ignition coil when you ignite your engine. This coil increases the voltage level from twelve volts to about 6,000 volts because it’s a compact electrical transformer.

Where Is a Vehicle’s Ignition Coil Located?

Your vehicle’s make and model determine the location of your ignition coil. Most cars have their ignition coil connected to each spark plug on the engine block top.

In some other vehicles, there is an individual coil that ignites all the spark plugs in the vehicle’s engine. Also, you can have ignition coils cluster in one pack on some vehicles.

What Causes Ignition Coils to Fail?

Recent ignition coils are designed robustly and can go for years without replacement. However, just like other parts, coils wear out over time. The reasons include:

1. Excessive Heat

Coils are exposed to severe heat from the car’s engine because of their location. The quantity of heat produced by the vehicle’s engine can place the plastic and metal parts of your coils under undue stress. In addition, the ability of your coil to convert low voltages to high voltages is reduced by thermal expansion.

2. Excessive Vibrations

While running, the engine generates a substantial vibration amount. Because the coils are installed directly on the spark plugs, they are exposed to severe vibrations.

These vibrations, over time, lose the coil assembly connection. When the coil connections are loose, there will be an inhibition of current flow between the coil’s conductive components.

3. Moisture and Contamination

The wearing out of the ignition coil is mostly caused by contamination and moisture. In addition, the coils could be contaminated with coolant and oil if the seals get broken because they are installed inside the engine.

Corrosion or electrical component shortening could happen when moisture drips into the vehicle’s coil. Apart from damaging the coils, leaks from broken gaskets and seals could cause damage to the entire engine.

4. Excessive Spark Plug Gap

The coil current must bridge the gap between the vehicle’s plug electrode for spark generation by the spark plugs. If the gap gets wider than proposed, the coils may have to function harder to produce a strong current that will bridge the widened gap. This causes stress to the coil parts and slows acceleration.

5. Worn Cables

For older cars, the ignition cables transmit current to the car’s spark plugs from the coils. Damage to cables may be either due to tear and wear or severe heat in the engine chamber.

In addition, faulty cables have increased resistance. If ignored, this increase in resistance could lead to the ignition coil burning out.

Also Read: RPM Going Up And Down At Idle (Causes & Solutions)

How to Test an Ignition Coil

Bad Ignition Coil Symptoms

If the ignition coil testing is done incorrectly, it could be dangerous. You can go for the professional services of an expert if you don’t know how an ignition coil can be tested safely.

Ignition coil issues can be checked by conducting an OBD-II check, as stated in the “check engine light” segment. Engine misfires are indicated with codes P0300 – P0312, while ignition coil problems are indicated with P0350 – P0362.

You may have to look for other types of testing for the ignition coil. The ignition coil location differs from car to car, so you will have to search online or check your car’s owner manual to ascertain the ignition coil position in your vehicle. Also, all precautionary measures must be observed to avoid electrocution.

When you locate the ignition coil, you could perform a physical examination for any damage signal. Checking the wiring of your ignition coil is the easiest thing to do.

If any wire is deteriorated or damaged, the ignition coil issue may be the source. You could also inspect the coil connector and harness for defects, especially loose connections and bent terminal pins.

If no issue is detected, you can go ahead and take out the ignition coil from your engine and perform a visual examination for the damage signal. Pay attention to moisture signs because liquids can cause damage to ignition coils.

You can carry out other tests if you own a CNP ignition coil. For this type of test, always use tools that are insulated and put on heavy rubber gloves.

  1. Switch the vehicle’s engine off.
  2. Take the spark plug cable off.
  3. Connect the plug cable to a new spark plug.
  4. Use insulated tools to hold the threaded portion of the plug to the engine’s metal part.
  5. Take off the fuse from your gas pump using the right tools.
  6. Engine cranking.

Once you are done with the engine crank, look for a blue spark around the spark plug gap. The presence of a blue spark will signify that the ignition coil is in perfect working condition.

If the blue sparks are absent or you can only see an orange spark, this indicates that the ignition could have an issue. Once you are done, reinstall the components to their correct positions.

Depending on your expertise level or type of ignition coil, some other tests can be performed on the ignition coil.

Ignition Coil Replacement Cost

The model and make of a vehicle determine the average cost of a new coil. Most coils are as affordable as $75. Meanwhile, others could be in the range of $300. If you consult the service of a professional, then the labor cost will be around $50 – $100 per hr.

So, you can estimate to pay about $150 – $200 if you decide to take the vehicle to a mechanic workshop for the replacement. If you have plans to consult a dealer, expect an increased amount.

How to Replace Ignition Coils?

A faulty coil replacement is quite simple; an average individual with basic automobile knowledge can do it. The general procedure is outlined below; you may decide to try it someday:

  1. Pull your vehicle over and turn your engine off.
  2. Open the bonnet and take the engine covers off if connected.
  3. Allow the engine to cool so that you can easily use bare hands on it. Find the coil in your engine. It can be found easily when you trace the harness that binds the coil and onboard computer together. The coil number varies from four, six, eight, ten, or twelve, depending on the engine type.
  4. Take off the connector from every coil assembly. Take notes of the connector’s position relative to the ignition coils. You will need this during reinstallation.
  5. Each ignition coil should be carefully pulled out of its position above the plugs. You would need to take off the bolts if they were fastened with a bolt so that the coils can be free.
  6. Place the new coil in place and ensure to push it all in. Note: Many replacement coils have the dielectric grease pre-applied. If your new coil is not greased, you can apply the dielectric grease on the coil assembly’s boot.
  7. After the coil’s installation, the connectors should be reconnected to the coils. Ensure to fuse each coil to its corresponding connector properly. Wrongconnections could lead to the firing order going out of control, resulting in destructive engine damage.
  8. Ignite your engine and observe the “Check Engine Light” if it is blinking.
  9. Use an OBD2 scanner to scan for error codes.
  10. If your “check engine” warning lights refuse to go off, and you cannot find any error code on the computer, take the car for test driving.
  11. Inspect for stalling, misfires, and other signals related to a faulty coil. If nothing is found, congratulations. Your car’s coils have been changed successfully.

Bad Ignition Coil Symptoms

Is It Ok to Drive With a Bad Ignition Coil?

No. Driving with a faulty ignition coil is not recommended. Driving to a mechanic workshop is the only recommendation. Faulty coils have to be replaced immediately. Driving with defective coils could lead to bad driving situations and cause damage to other vehicle parts.

Also Read: Check Charging System (Meaning, Causes and Solutions)

Frequently Asked Questions – Bad Ignition Coil Symptoms

What happens if one ignition coil goes bad?

Older cars use one coil to provide voltage to each plug, whereas recent cars have a single ignition coil for each cylinder. In the older vehicles, if the single-coil fails, no cylinder collects spark, which could lead to the vehicle cranking without start.

Can I drive with bad ignition coils?

Yes, driving with a bad ignition coil is possible if it is essential, although you will observe the poor running of the vehicle. However, if ignored, the ignition coil issue could lead to severe damage to other components of your vehicle, such as the catalytic converter.

Will a bad ignition coil throw a code?

When an issue is detected with the ignition coil, the check engine light will be illuminated, and any related error codes will be logged. Either your engine stalls or performs poorly as a pack of coil that is firing improperly will lead to incomplete combustion in the engine.

Can I replace just one ignition coil?

You can replace all the coils at once or just one at a particular period. Replacing the entire spark plugs with the coils will be recommended so that you do not repeat the process twice.

How often should ignition coils be replaced?

Ignition coils have only a lifespan; they don’t have intervals for servicing. They do not have a specific age or mileage for replacement. Replacement can be done only when they become faulty. If you observe any form of cracks on the epoxy or plastic and probably misfire, then that is the right time to get the ignition coils replaced.

How long should an ignition coil last?

The average lifespan of the coil is about 100,000 miles or sometimes more. The part does not wear out easily, yet different reasons could lead to its failure.

Should I replace ignition coils with spark plugs?

Depending on the situation, Spark plugs are the common replacement parts alongside ignition coils. However, spark plugs that are worn out can result in undue pressure on the ignition coil, and this often leads to some extension in labor needed for the replacement of both parts.

Conclusion – Bad Ignition Coil Symptoms

The ignition coils play a vital role in your car so much that the car won’t run properly without them. The signals of worn-out coils should not be avoided, and coil issues could be time-sensitive.

Once the problem is ignored, it could accelerate wear on some other parts, leading to more expensive repairs.

You will need to act as fast as possible to avoid further damage, either by taking your car to an expert or replacing it yourself since the steps for replacement are quite easy.

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