8 Engine Problems That Start Small But Cost Thousands to Fix

February 25, 2025

As a former mechanic, I know how expensive engine problems can get. Ignoring some of the minor issues can actually wind up costing you a ton of money. So, before you dismiss these eight engine issues that start out as small problems, think twice. They could wind up costing you a boatload of money.

1. Overheating Issues

You should never, ever ignore your car overheating. At the very least, you will need to top up your coolant, but you might have a leak or a faulty thermostat. Either way, ignoring this issue can lead to some serious problems. You may wind up replacing a head gasket, which can cost thousands (especially if there’s additional damage to the engine. So, it’s important to keep an eye on your coolant levels and watch for signs of overheating like steam or high-temp readings.

2. Oil Leaks

A few drops of oil under your car may not seem alarming, but it could signal a bigger issue. Leaking oil can lead to low oil levels, increasing friction and causing engine wear. Over time, this can damage critical components such as the crankshaft and camshaft. Repairing internal engine damage is far more expensive than fixing a simple leak.

3. Ignition Coil Failure

A failing ignition coil can cause misfires, poor fuel efficiency, and sluggish acceleration. Left unchecked, this can put extra strain on the catalytic converter, leading to a costly replacement. Ignition coils are relatively inexpensive to replace, but ignoring the issue can lead to further engine problems. Symptoms include rough idling and trouble starting your vehicle.

4. Timing Belt Wear

The timing belt controls the synchronization of engine components, and its failure can be catastrophic. A worn timing belt can snap, causing valves and pistons to collide. This can result in a complete engine rebuild, which can cost thousands. Most manufacturers recommend replacing the timing belt every 60,000 to 100,000 miles.

5. Clogged Fuel Injectors

Fuel injectors can become clogged due to debris and carbon buildup, leading to poor fuel efficiency. A partially clogged injector can cause the engine to run lean, increasing the risk of overheating. Over time, this can lead to internal engine damage and expensive repairs. Using high-quality fuel and adding fuel injector cleaner periodically can help prevent this issue.

6. Failing Oxygen Sensor

A malfunctioning oxygen sensor can cause your engine to burn fuel inefficiently. This leads to increased emissions and can eventually damage the catalytic converter. A replacement catalytic converter can cost over $2,000, making early oxygen sensor replacement crucial. Symptoms of a failing oxygen sensor include poor gas mileage and a check engine light.

7. Worn Spark Plugs

Old spark plugs can cause engine misfires, rough idling, and sluggish acceleration. Misfires put additional strain on the ignition system and fuel injectors. Over time, this can lead to costly repairs, including damage to the catalytic converter. Replacing spark plugs is an inexpensive maintenance task that can prevent bigger issues. Most manufacturers recommend changing spark plugs every 30,000 to 100,000 miles.

8. Low Coolant Levels

Running low on coolant can lead to overheating and severe engine damage. A minor coolant leak can go unnoticed until it causes major problems. Without proper coolant levels, the engine can develop cracks or warping in critical components. Routine coolant checks and flushing the system periodically can prevent expensive repairs.

Prevention Saves Money

Catching these small engine problems before they become a big issue can save you thousands of dollars. As always, routine maintenance goes a long way with your vehicle. Bringing your car in on a regular basis will help you catch some of these issues early and help you avoid costly breakdowns. So, don’t ignore these eight things. They could become a huge headache for you down the road.

5 Vehicles with Advanced Brake Assist Features You Didn’t Know You Needed