If your car takes iridium spark plugs, or you DIY your tune-ups by buying plugs in the aftermarket, get ready to unlock a new fear. Just like any other wholesale-fueled market, cheap knockoffs are becoming a real issue in the automotive parts supply chain. However, unlike otherwise “harmless” products that you only wear or decorate your home with, counterfeit car parts can cause catastrophic damage to your car’s engine. That seems to be what’s happening to folks thinking they’re installing good spark plugs, particularly ones with NGK and NTK part numbers.

It happens like this: someone somewhere cobbles together spark plugs built to closely ape the good brands. The most damaging flaw in these plugs is the low-quality center electrode. NGK electrodes are iridium. The dupes, though, are so crappy that they actually melt during an engine’s normal combustion activity. The effect leaves bits of electrode knocking around in the cylinder.

The calamity can bend valves, which essentially ruins the engine from the inside.

A recent Reddit conversation in r/MechanicAdvice helped one Jeep owner conclude that a set of counterfeit plugs likely bent a valve in cylinder two. He found out the center electrode melted and fell off into the cylinder.

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Otherwise, poor spark plug build quality can cause engine performance issues. Left alone, these misbehaviors just really mess with a car’s longevity.

The issue is so severe that Niterra, the company that manufactures NGK and NTK spark plugs, has a whole page on identifying fakes.

If you’re a DIYer, be sure to check out the company’s advice so you don’t end up installing dupes. If you take your car to a shop, though, making sure you’re getting genuine spark plugs can be a bit trickier. Do your research or at least ask the shop to install OEM spark plugs from a reputable supplier. If not the dealer, ensure the parts supplier offers a good warranty. Then, if a catastrophic engine issue happens during the warranty period, add faulty spark plugs to your list of possible culprits.

Drivers might have a hard time getting engine damage caused by counterfeit plus covered under any kind of warranty.

First off, it might be difficult to even determine the root cause of internal engine damage. The diagnostic flowchart typically requires a series of initial evaluations. A compression test is usually the place to start. It’ll tell a mechanic whether each engine cylinder can create and hold pressure individually. Then, at least some dissection of engine components needs doing. Usually, a “qualified” party has to do all of this during the formal claim process.

These days, many folks simply walk away from a surface-level blown engine diagnostic and move on to a different vehicle.

Alternatively, say you decide to keep your car and replace the engine. Still, the replacement process doesn’t require a mechanic to tear down the damaged one. If it’s a straightforward engine swap, it’s just removing the entire assembly and then installing a whole new one.

If you opt for a rebuild, then the mechanic (or you) will likely identify signs of the issue at some point in the repair procedure.

In any case, you’d need either a good factory warranty, an aftermarket warranty, or a shop warranty that would cover the possibility of counterfeit spark plug failure. Or, at least cover the end result without requiring an investigation. Personally, after filing dozens of warranty claims for shop customers over the years, I’d guess a bunch of finger-pointing or thrown-up hands-style hilarity would ensue if the idea were even brought up.

I’d assume parts and labor claims submitted by DIYers would be a challenge to get paid out at all. Especially if you went with products from a digital wholesaler, like an off-the-beaten-path parts supplier.

All told, the Niterra FIY page has me wondering just how many motorists have already unknowingly suffered engine failure shortly after counterfeit spark plug replacement.