What a grid heater delete does to your 6.7 Cummins engine

A grid heater delete removes the intake air heater that Cummins installs on 6.7L diesel engines to warm incoming air during cold starts. When you delete it, your engine loses that preheating function entirely. The engine will still start in cold weather, but it relies on compression heat alone — the same way older diesel engines did before grid heaters became standard.

The grid heater sits in the intake manifold and draws significant electrical current when the engine is cold. Deleting it means removing that component and the wiring that powers it, then reprogramming the engine control module (ECM) to stop calling for heat that no longer exists. Some owners replace it with nothing; others install an aftermarket alternative like a block heater or inline heater.

Whether this makes sense depends on your climate, how you use the truck, and what you're trying to solve. The decision is not straightforward "delete good" or "delete bad" — it trades one set of problems for another.

Key Takeaways

  • Grid heater deletes eliminate a known failure point on 6.7 Cummins engines, but cold-start performance and emissions depend on ambient temperature and engine load.
  • Removing the grid heater reduces electrical draw and frees up engine bay space, but you lose the factory cold-start information that Cummins engineered into the truck.
  • In temperatures below 20°F, a truck without a grid heater will have harder starts, longer cranking times, and higher white smoke on initial ignition.
  • Most tuning companies that offer grid heater deletes also sell ECM tunes that adjust fuel injection timing to compensate for the missing heat, though results vary by ambient temperature.
  • A block heater or inline heater can restore cold-start performance after a grid heater delete, but adds cost and requires either a 120V outlet or a second electrical modification.

Why grid heaters fail on 6.7 Cummins trucks

The grid heater on 6.7 Cummins engines is a common failure point. The heating element itself can burn out, the relay that controls it can stick or fail, and the wiring harness can corrode or develop shorts. When the grid heater fails, the engine control module detects the fault and stores a diagnostic trouble code — usually P0088 or a grid heater-specific code — and the check engine light comes on.

Replacement grid heaters are not cheap. A factory Cummins grid heater assembly costs between $400 and $800 depending on the year and where you buy it, and labor to remove and install it adds another $200 to $500 at a diesel shop. Some owners face repeated failures within a few years, which is why the delete option appeals to them: remove the part that keeps breaking, and the problem stops.

The trade-off is that you're removing a component Cummins designed to help the engine start reliably in cold weather. Deleting it solves the failure problem but creates a different one: cold-start performance in freezing temperatures.

Cold-start performance without a grid heater

In mild climates — above 40°F — the absence of a grid heater is barely noticeable. Diesel engines compress air to ignite fuel, and at moderate temperatures, compression heat alone is usually enough. The engine will crank normally and fire up without hesitation.

Below 40°F, the difference becomes apparent. Cranking takes longer because the air entering the cylinder is colder, and the fuel takes longer to ignite. Below 20°F, a 6.7 Cummins without a grid heater will crank noticeably harder and may require multiple attempts to start, especially if the battery is weak or the engine oil is thick from cold. You will also see white smoke from the exhaust for the first 30 seconds to a minute — unburned fuel exiting as vapor — because the combustion temperature is lower than normal.

If you live in a region where winter temperatures regularly drop below zero, a grid heater delete without a replacement heating method is a genuine inconvenience. If you park in a garage or heated shop, or if you live somewhere that rarely sees freezing nights, the impact is minimal.

Electrical and performance gains from removing the grid heater

The grid heater draws a large amount of current when it is active — typically 50 to 100 amps during the warm-up cycle. On a truck with a marginal battery or an older alternator, that draw can stress the electrical system. Removing the grid heater eliminates that load, which can improve cold-weather electrical stability and reduce strain on the battery during starting.

Deleting the grid heater also frees up physical space in the intake manifold and removes wiring and connectors from the engine bay. For owners building heavily modified engines or installing aftermarket intake systems, that space and simplicity can matter. The weight savings is negligible — the grid heater assembly weighs only a few pounds — but the electrical simplification appeals to some builders.

Some tuning companies claim that deleting the grid heater and adjusting fuel injection timing in the ECM can improve fuel economy or throttle response. These claims are difficult to verify independently, and results depend heavily on driving habits and ambient temperature. A truck that idles less and operates at steady highway speeds may see a small improvement; a truck that sits in traffic or operates in very cold conditions may see no benefit or even worse cold-start behavior.

ECM tuning and compensation strategies after a delete

Most shops that offer grid heater deletes also provide an ECM tune — a reprogramming of the engine control module — that adjusts fuel injection timing and quantity to compensate for the missing heater. The idea is to inject more fuel earlier in the combustion cycle, which generates more heat and helps ignition occur more reliably in cold air.

This strategy works to some degree, but it is not a perfect replacement for the grid heater. A grid heater warms the incoming air before it enters the cylinder; a fuel-based compensation strategy relies on the fuel itself to generate the heat needed for ignition. In very cold temperatures, the difference is noticeable. The tune may reduce cranking time and white smoke compared to a delete with no tune, but it will not restore the cold-start performance of a truck with a functioning grid heater.

Additionally, running a richer fuel mixture during cold starts can increase soot production and put extra stress on the fuel injectors and combustion chamber. Over time, this may contribute to carbon buildup or injector wear, though long-term data on this specific scenario is limited.

Block heaters and inline heaters as alternatives

If you delete the grid heater but want to restore cold-start performance, you can install a block heater — an electric heating element that screws into the engine block and warms the coolant before starting. A block heater requires a 120-volt outlet and must be plugged in for 4 to 8 hours before you start the engine in cold weather. It is inexpensive (typically $50 to $150 for the heater itself) and effective, but it only works if you have access to power and remember to plug it in.

An inline heater is a heating element installed in the coolant line or intake manifold that can operate on 12 volts from the truck battery or from a separate power source. Inline heaters are more expensive ($300 to $800 installed) and require additional wiring, but they do not depend on an external outlet. Some aftermarket inline heaters can be programmed to set up automatically when the engine temperature drops below a set point.

Both options restore some cold-start information, but neither is as efficient or as integrated into the engine management system as the factory grid heater. They are compromises — better than nothing, but not equivalent to the original design.

Emissions and warranty implications

Deleting the grid heater changes the emissions profile of the engine. The grid heater helps the engine reach proper combustion temperature quickly, which reduces unburned hydrocarbons and particulates in the exhaust during cold starts. Without it, white smoke and higher emissions are normal for the first minute or two of operation, especially in cold weather.

If your truck is still under the factory powertrain warranty, a grid heater delete may void that warranty. Cummins and Dodge can deny warranty claims on engine components if they determine that a delete or tune contributed to the failure. Some shops will perform the delete without documenting it, but that does not protect you if a dealer discovers the modification during service.

If your truck is out of warranty, emissions implications are less of a legal concern, though they remain an environmental one. Many states do not actively police diesel truck modifications, but some regions have stricter rules about aftermarket engine work.

Frequently Asked Questions

Will my 6.7 Cummins start without a grid heater in winter?

Yes, it will start in most winter conditions, but with difficulty below 20°F. Cranking will take longer, you may need multiple attempts, and white smoke will be visible for the first minute. In mild climates or if you park in a garage, the impact is minimal.

Can I delete the grid heater and keep the factory ECM tune?

Technically yes, but it is not recommended. The factory tune expects the grid heater to be present and active. Deleting the heater without adjusting the tune can cause rough idle, hesitation, and poor cold-start performance. Most shops that perform deletes also reprogram the ECM to account for the missing component.

How much does a grid heater delete cost?

A delete with ECM tune typically costs $500 to $1,200 depending on the shop and the complexity of the tune. A block heater is cheaper ($50 to $150 for the part), while an inline heater runs $300 to $800 installed. Prices vary by region and shop.

Will deleting the grid heater improve my fuel economy?

Some tuning companies claim small improvements, but independent verification is limited. Results depend on driving habits, ambient temperature, and the specific tune used. Cold-weather fuel economy may actually worsen due to longer cranking times and richer fuel mixtures during startup.

Is a grid heater delete reversible?

Mechanically yes — you can reinstall a grid heater if you change your mind. However, the ECM tune is permanent unless you reflash the module back to factory settings. Reflashing costs $200 to $400 at most diesel shops.