6.7 Cummins Grid Heater Delete: What It Is, Why Owners Do It, and What to Consider

The 6.7 Cummins is a capable diesel engine found in Ram 2500 and 3500 trucks from 2007 onward. Like most modern diesels, it relies on a grid heater — also called an intake heater — to warm incoming air before cold starts. Some owners remove or bypass this component entirely, a modification known as a grid heater delete. Here's how the system works, why the delete exists as a modification, and what factors shape whether it makes sense for any given truck.

How the 6.7 Cummins Grid Heater Works

Diesel engines don't use spark plugs. Instead, they ignite fuel through compression heat — air is compressed so tightly in the cylinder that it becomes hot enough to combust diesel fuel on its own. In cold weather, ambient air entering the engine is too cold for reliable ignition without help.

The grid heater solves this. It's an electric resistance element mounted in the intake manifold. When you turn the key to the "on" position, the system draws current from the battery, heats the grid element, and warms incoming air before the engine cranks. The "Wait to Start" light on the dash indicates the grid heater is doing its job.

On 6.7 Cummins trucks, the grid heater draws significant amperage — often 400–600 amps at peak — and the system is controlled by a relay and monitored by the ECM. Failures are relatively common, often showing up as hard cold starts, a "Wait to Start" light that never comes on, or fault codes like P0540 (intake air heater circuit).

What a Grid Heater Delete Actually Does

A grid heater delete removes the heater element and replaces it with a smooth adapter plate or delete pipe that maintains airflow continuity through the intake without the restriction the grid creates. Some owners also delete the associated relay and wiring, while others leave the electrical components in place.

The modification is popular for a few reasons:

The grid heater can fail and become a partial intake restriction even when not energized
Replacement costs for the heater element and relay can run into several hundred dollars depending on parts and labor, though prices vary by region and shop
Some performance-focused owners believe the grid adds unnecessary restriction in a built or modified intake tract
Fleet and work truck operators may prioritize simplicity and fewer electrical failure points

It's worth being clear: a grid heater delete is not a performance upgrade in the traditional sense. It doesn't add horsepower or torque directly. Its appeal is largely reliability and cost avoidance — particularly for trucks that have already experienced grid heater failure.

The Cold-Start Trade-Off ❄️

This is the central trade-off, and it's real. Without a functioning grid heater, cold-start behavior changes. How much it changes depends on several variables:

Factor	Effect on Cold Start Without Grid Heater
Ambient temperature	Below 20°F, cold starts become noticeably harder
Engine condition	Worn engines with lower compression struggle more
Fuel quality	Winter-blend diesel helps; summer-blend gels and ignites poorly in cold
Intake/exhaust modifications	Upgraded glowplug-style systems can partially compensate
Oil viscosity	Thicker oil in cold weather increases cranking resistance

Owners in warm climates — the American Southwest, the South, mild coastal regions — often report that the delete causes no meaningful issues year-round. Owners in Minnesota, Montana, or Canada who operate in sub-zero temperatures tell a different story. Geography matters significantly here.

Some owners who perform the delete also install a block heater or battery tender routine as a backup cold-start strategy, especially if they park outside in winter.

Legal, Emissions, and Inspection Considerations 🔧

This is where the modification gets more complicated, and it varies significantly by state.

The grid heater itself is not directly part of the emissions control system — it's an intake air heating device, not a catalyst or filter. That said:

Removing or altering intake components can trigger OBD-II fault codes, which may cause a check engine light
Some states use OBD-II readiness monitors as part of emissions testing — a grid heater fault code or cleared monitors can cause a test failure
A few states require visual inspection of engine components, which could flag aftermarket intake hardware
Modified trucks that compete in dyno events or sanctioned racing may face specific ruleset restrictions

States with no emissions testing, or those that exempt older diesels or high-GVWR trucks, face fewer of these concerns. States with strict OBD-II testing programs are a different situation entirely.

Tuning is often part of the equation. Many owners who delete the grid heater also run an aftermarket tune that clears the associated fault codes and adjusts cold-start fueling to compensate for the missing intake heat. Without a tune, a deleted grid heater may leave persistent fault codes active.

What Shapes the Outcome for Individual Owners

No two 6.7 Cummins owners are in the same position. The factors that determine whether a grid heater delete is straightforward or complicated include:

Climate and typical operating temperatures
State emissions and inspection requirements
Whether the truck is tuned or stock
How the truck is used (daily driver, work truck, weekend tow rig, competition)
Current condition of the grid heater — whether it's failed, failing, or functioning normally
Budget — delete kits and associated tuning have their own costs

A stock, warranty-covered truck used as a daily driver in a state with OBD-II testing is in a very different position than a high-mileage, fully modified work truck in a state with no emissions program.