Grid heater failure is associated with the 6.7L Cummins Turbo Diesel engine found in RAM 2500-5500 trucks, spanning model years from 2007-2024. The grid heater is an essential component designed to warm incoming air during cold starts, aiding combustion in Diesel engines where ignition relies on heat and pressure rather than a spark. However, a well-documented failure has led to significant engine damage in an alarming number of vehicles.
Pre-2007: The Precursor Era
Before the 6.7L Cummins debuted in Ram trucks, earlier Cummins engines like the 5.9L had their own infamous failure points, such as the "Killer Dowel Pin" in the 12-valve models (1994-1998). This pin could dislodge and damage the engine, setting a precedent for small components causing big problems. Although the 5.9L did use a grid heater to aid cold-start aids (like glow plugs), issues were not documented nor was it believed to be a problem.
2007: Introduction of the 6.7L Cummins and Grid Heater
The 6.7L Cummins Turbo Diesel was introduced in RAM 2500-5500 trucks for the 2007.5 model year, replacing the 5.9L. It featured a larger air intake grid heater—a resistive element in the intake manifold designed to warm incoming air for cold starts, improving combustion in the absence of spark plugs. The grid heater relied on a small bolt or stud to secure its high-amperage (up to 200 amps) electrical connection. The grid was electrified beginning at 50°F and below. As temps decreased, the truck's Engine Control Module increases the time that the heater is energized. At the time, there were no widespread reports of issues, likely due to the newness of the design and limited mileage accumulation.
2007–2012: Early Years and Sporadic Failures
During the initial years (2007–2012), the grid heater system operated without significant attention. However, anecdotal evidence from forums suggests rare instances of bolts loosening or breaking, possibly due to heat cycling and vibration. These early failures were likely underreported, as they occurred outside warranty periods or were misdiagnosed as general engine issues. The problem didn’t yet have a name or a pattern, and RAM/Cummins issued no recalls or technical service bulletins (TSBs) specific to the grid heater bolt during this period.
2013–2016: Recognition of a Pattern
By 2013, as more 6.7L-equipped trucks accumulated mileage (often exceeding 100,000 miles), reports of grid heater bolt failures began surfacing on forums like CumminsForum.com and Reddit’s r/Cummins. Owners described sudden engine knocks, power loss, or diagnostic trouble codes (DTCs) like P2609 ("Intake Air Heater System Performance") and P0542 ("Intake Air Heater Circuit High"). Upon inspection, mechanics found that the grid heater bolt or nut had detached, fallen into the intake manifold, and entered cylinder #6, causing piston, valve, or head damage. Costs ranged from $6,000 for repairs to $17,000–$30,000 for full engine replacements. The issue appeared across all model years from 2007 onward, suggesting a design flaw rather than a specific batch problem.
A video titled "Cummins Grid Heater Bolt FAILURE" by Full Throttle Fabrication (uploaded circa 2016) shows a damaged piston from a 2012 Ram 6.7L, attributing it to a grid heater bolt failure, one of the first visual documentations online.
2017–2019: Growing Awareness and Aftermarket Response
As awareness grew, aftermarket companies took notice. By 2017, products like grid heater delete kits emerged, aimed at removing the heater entirely for owners in warmer climates, though this sacrificed cold-start performance. In 2018–2019, a more robust solution appeared:
Banks Power introduced the Monster-Ram intake system, replacing the stock grid heater with a High-Flow Billet Intake Plate, eliminating the problematic bolt. The kit included a high-efficiency coil heater threaded vertically into the top of the intake casting. The reliable 60-amp coil heater was used in early Duramax engines.
YouTube Video Reference "Cummins Grid Heater Killer Bolt Issue - Amps & Voltage on engine start" by Marion Blair (uploaded 12, 2019) discussed the causes of the failure, attributing it poor metallurgical design of the grid heater assembly, leading to ~225 amps arching across from the bolt to ground.
2020–2021: Peak Frustration and Recall Hints
By 2020, owner frustration peaked, with reports of failures in newer trucks (e.g., a 2020 RAM 3500 with 118,000 miles cited on ramforum.com). Social media and YouTube amplified the issue, with mechanics like those at Gillett Diesel Service, ProTech Diesel, ProMac Diesel, Banghard Diesel, Willis Diesel, and FTM Diesel, noting a rise in grid heater-related repairs. In late 2021, Stellantis (RAM’s parent company) issued a recall (Y08/Y76) for 2021–2022 RAM trucks due to a related but distinct issue: grid heater relays sticking, causing overheating and fire risks. This affected 306,165 vehicles but didn’t address the bolt failure directly, suggesting RAM viewed it as a separate, rarer problem.
YouTube Video Reference: "This is the bolt that kills RAM trucks" by Banks Power (uploaded Mar 18, 2023). This video demonstrates the "jiggle test" to check bolt looseness, a grassroots diagnostic method that gained traction.
2022–2023: Refinement and Debate
In 2022, the issue became a hot topic in diesel communities. Forums like Turbo Diesel Register and Forest River Forums debated its frequency—some called it "very rare" (Geno’s Garage), while others cited multiple local cases (ProTech Diesel in Kamloops, British Columbia reporting 4–5 failures in 2023 alone). Banks Power released more cautions, detailed videos, and articles linking DTCs P2609/P0542 to bolt degradation. Meanwhile, RAM updated the grid heater relay design in 2023–2024 models, but grid heater assembly itself remained unchanged, fueling speculation about whether the core issue was being ignored.
YouTube Video Reference: "Here’s how you test to see if the nut and bolt in your factory RAM 6.7L Cummins grid heater is loose" by Banks Power (uploaded circa 2022). This short clip shows the jiggle test in action, reinforcing preventative awareness. [Search Banks Power channel for this specific upload.]
2024: Ongoing Concern and Solutions
As of March 4, 2025, grid heater bolt failure remains an unresolved design quirk in 2007–2024 RAM 6.7L Cummins trucks. RAM has not issued a recall for the grid heater assembly, possibly due to its perceived rarity (although Banks Power documented over 200 failures, some with as few as 40,000 miles). Owners continue to face high repair costs, with used engines at $10,000 and new ones at $17,000-$30,000. Fleet owners who have succumbed to the failure have suffered even greater losses due to downtime and maintenance. Aftermarket fixes dominate the conversation—BD Diesel’s Killer Grid Heater Upgrade Kit emerged, claiming to fix the bolt problem. However, BD’s design retained a failure point: its revised assembly could still loosen under high current and vibration, potentially dropping debris into the engine—mirroring the factory flaw’s damage potential. Whether it’s the stock grid heater or BD’s "fix," it’s still a game of Russian roulette a growing number of RAM owner refuse to play. Since 2017, tens of thousands of Banks Monster-Ram Intake Systems have been installed with no reported failures. An added bonus, says Banks, is improved throttle response and fuel economy thanks to a reduction in airflow restrictions.
2025: Cummins Changes Design
For the 2025 model year, RAM introduced major updates to the engine including removing the grid heater in favor of glow plugs, a move that stunned Cummins enthusiasts. Glow plugs have been used in Duramax, Ford, and other popular Diesel engines for decades. It is surmised that Cummins wanted to increase air mass into the intake manifold in order to increase power and meet emissions standards. Opening up the inlet on the intake manifold required the removal of the grid heater. No longer could the intake air be necked down to a narrow passageway in order to pass over the grid heater element.
YouTube Video Reference: "How to prevent RAM Cummins 6.7L engine failure due to stock grid heater" by Banks Power (uploaded Jun 28, 2022). Gale Banks details the Monster-Ram's advantages and contrasts it with ill-preforming competitors.
