If you’ve owned a Cummins long enough, you’ve probably heard the horror stories about Cummins grid heater failure, specifically the infamous grid heater bolt that loves to yeet itself into cylinder #6. It’s the kind of problem that keeps diesel owners awake at night and keeps tow truck drivers in business.

For years, the grid heater was supposed to be the hero of cold starts. Instead, it turned into one of the most failure-prone parts on the engine. Now, with the 2025 Cummins redesign, the company is ditching the grid heater entirely in favor of glow plugs. According to Cummins, the switch has nothing to do with the reliability issues… Sure… we all believe that. 

Let’s break down the real story behind grid heater bolt issues, how owners have been fixing them, and why the glow plug era is a huge step forward in Cummins reliability.

What Causes Cummins Grid Heater Failure?

The weak point has always been the grid heater bolt, which endures:

• Repeated heat cycles
• Constant engine vibration
• Long-term corrosion

Eventually, that bolt gets tired of living and decides to make a break for it. When it loosens or melts, it falls into the intake, rolls its way toward cylinder #6, and suddenly you’re dealing with catastrophic Cummins engine failure instead of a simple cold-start aid.

The symptoms of grid heater failure might start as odd noises or a check engine light, but the end result can be:

• Bent valves
• Damaged pistons
• Cracked heads
• A five-figure repair bill

It’s one of the most discussed topics in diesel forums because it’s both common and completely preventable!

How Owners Have Avoided Grid Heater Problems

Instead of waiting for Cummins to fix the issue, many owners took matters into their own hands with the Banks Monster Ram Intake: currently the most popular aftermarket solution to grid heater failure.

Why? Because it:

• Removes the factory grid heater completely
• Eliminates the failure-prone grid heater bolt
• Uses a safer coil heater design
• Improves airflow for more power

The Banks Monster Ram Intake isn’t just a performance mod, it’s an insurance policy against grid heater failure. Countless owners report discovering corroded or loose bolts during removal… meaning they avoided disaster by hours or days.

2025 Cummins Glow Plugs: A Better (and Safer) Cold-Start System

Here’s where things finally get good. For the 2025 Cummins 6.7L, the engine now uses glow plugs instead of a grid heater. This eliminates the entire failure-prone assembly and dramatically improves cold start performance.

Glow plugs offer:

• Faster cold starts (no more 20–30 second waits)
• Zero risk of heater hardware entering the engine
• Better thermal efficiency
• Basically just a simpler, safer cold start system!

Officially, Cummins claims the switch to glow plugs has nothing to do with the years of grid heater bolt failures. Totally unrelated… Pure coincidence. The timing just happens to perfectly align with a widespread reliability problem they definitely aren’t acknowledging… Sure.

Regardless of the corporate explanation, the end result is clear: the number one cause of catastrophic Cummins grid heater failure is gone for good on 2025+ models.

What This Means for Cummins Owners

If You Own a Pre-2025 Cummins

You absolutely should consider upgrading to a Banks Monster Ram Intake or another grid heater delete solution. This remains the best way to prevent grid heater bolt failures and protect your engine’s long-term reliability.

If You’re Buying a 2025+ Cummins

Congratulations, you’re entering the glow plug generation (just a few decades late). Your cold starts will be faster, your intake will be cleaner, and the most notorious failure point has been eliminated by design.

If You Are Cummins

Hey, better late than never. Everyone appreciates the upgrade, even if you didn’t want to put it in writing that the grid heater bolt occasionally tried to destroy entire engines.

The 2025 Cummins glow plug system is the cold start solution the platform should have had years ago. By eliminating the grid heater assembly, Cummins has finally put an end to one of the most infamous reliability issues in modern diesel trucks.

For owners of older models, aftermarket upgrades like the Banks Monster Ram Intake remain the best defense against grid heater failure. For new truck buyers, the glow plug era means faster starts, better efficiency, and most importantly, no more mystery bolts tumbling into cylinders.

The fix may have taken a while, but the glow plug update finally puts this long-running problem to rest.

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