Table of Contents

The CCV System on the 6.7 Cummins

How Blow-By Works

Every internal combustion engine produces blow-by. During combustion, a small amount of gas forces its way past the piston rings and into the crankcase. In a diesel with a high compression ratio, that volume grows with load, because cylinder pressure and heat both rise. Left unvented, that pressure finds the weakest seal to escape through.

Before 2007, heavy-duty diesels commonly vented this pressure to atmosphere through an open draft tube, so the oil mist dripped onto the road. That ended with model year 2007. Title 40 CFR 86.007-11(c) states that no crankcase emissions may be discharged directly into the atmosphere from any new 2007 or later model year diesel engine.

How the Factory System Handles It

Cummins answered the rule with a crankcase ventilation system that routes blow-by out of the valve cover, through a coalescing filter element, and into the intake ahead of the turbocharger. The filter element forces the vapor to change direction so oil droplets collect and drain back to the crankcase, while the remaining vapor goes to the intake and burns in the cylinders.

The filter element does not last forever. It is a service item with a set replacement interval, and a saturated element passes more oil into the intake tract than a healthy one.

What the Factory Service Schedule Says

This is the part most owner-written guides get wrong. The CCV filter element is not something you judge by eye and replace at "every other oil change." It is a mileage-based part with a specific interval, and the housing is sealed, so you cannot reliably read the saturation level of the internal media from the outside.

Model year CCV filter interval
2007.5 to 2018 Ram 2500 / 3500 67,500 miles (about 54 months)
2019 and newer Ram 2500 / 3500 75,000 miles (about 60 months)
Severe duty use (heavy towing, long idling, dusty conditions) Shorter interval, inspect well before the standard number

The element itself is an inexpensive part, and replacing it on schedule is far cheaper than dealing with the consequences of a restricted crankcase vent.

The "Perform Service" Message and Its Reset

When the truck reaches the CCV interval, the Electronic Vehicle Information Center (EVIC) triggers a "Perform Service" message. That message is the factory emissions maintenance reminder, and the CCV filter element is one of the items it covers. On 2007.5 to 2012 trucks, the Ram diesel supplement groups the EGR valve and EGR cooler cleaning into that same interval, so check what your model year's schedule lists.

Replacing the filter does not clear the message on its own. The reset is a manual pedal sequence:

  1. Turn the ignition to ON/RUN. Do not start the engine.
  2. Press and release the brake pedal twice.
  3. Fully depress and slowly release the accelerator pedal twice, within 10 seconds.
  4. Turn the ignition to OFF/LOCK.

If the message returns on the next start, the sequence did not take. Run it again, or have a shop clear it with a scan tool.

Related Diagnostic Codes

If the CCV filter clogs badly enough to restrict crankcase flow, the truck can set crankcase filter restriction codes, P1507 and P1508, which turn on the check engine light. Those codes point at the filter first, not at a reason to delete the system.

Symptoms of CCV Problems on a 6.7 Cummins

Before you decide on a reroute, confirm what is actually happening. These are the signs to look for.

  • Oil film in the intercooler boots and intake horn. A light mist is normal. Visible liquid oil pooling in the charge pipes is not. Pull the intake horn and look inside with a flashlight.
  • Oil vapor or pressure at the oil fill cap. With the engine at idle, remove the fill cap. Strong positive pressure or visible vapor means crankcase pressure is not being relieved.
  • Oil pushed out of the dipstick tube or weeping from seals. A clogged filter raises crankcase pressure, and that pressure pushes oil past the rear main seal, timing cover, or valve cover gasket.
  • Oil residue at the turbo compressor inlet. Vapor entering the intake passes through the compressor wheel first.

Important: Do not treat a reroute kit as a fix for a worn engine. Rising oil consumption, heavy blow-by, and oil pooling in the intercooler are also symptoms of worn piston rings, a cracked piston, or failed turbocharger shaft seals. A reroute cannot correct internal wear. If the truck has these symptoms, diagnose before you modify.

CCV Reroute Options

There are three practical configurations. They differ in where the crankcase vapor ends up, and that difference is where the legal exposure lives.

Setup Where the vapor goes Intake tract Notes
Factory OEM system Sealed loop back to the intake through the coalescing filter Some oil film builds over time Legal on public roads. Requires scheduled filter replacement.
Vent to atmosphere (VTA) Open hose to a breather filter under the truck Stays dry Simplest hardware. Vents untreated vapor to the air. Treated as a crankcase ventilation delete under federal rules.
Catch can, vented or closed loop Through a canister that separates oil, then to atmosphere or back to the intake Stays dry (vented) or mostly dry (closed loop) Adds a reservoir that must be drained on a schedule.

Vent-to-Atmosphere (VTA)

In a VTA setup, the factory CCV hose comes off the intake horn, the horn port gets capped with a block-off plug, and a new hose runs from the valve cover down under the truck to a small breather filter.

The benefit is a completely dry intake tract. The trade-offs are real. Crankcase vapor carries fuel and oil odor, and with the line exiting under the truck that odor can reach the cab when the truck idles or backs up. The vapor also cools as it travels and condenses into liquid oil that drips from the vent tip, leaving a film on the frame, steering, and transmission area and spotting the surface the truck parks on.

Catch Cans

A catch can sits inline in the ventilation path. Blow-by gas passes through the canister, where baffling, mesh, or coalescing media knocks the oil out of the vapor, and the collected oil drops to the bottom of the reservoir. Some setups vent the remaining vapor to atmosphere. Others, called closed loop, route it back to the intake so the factory vacuum path stays intact. The closed-loop version is the one to look at if you care about legal exposure.

The maintenance requirement is the catch. The reservoir has to be drained on a schedule, and how often depends on how much blow-by your engine makes. A hard-working truck or a high-mileage engine fills the can faster than a light-duty one. If the reservoir fills and backs up into the vent line, the ventilation path is blocked, which is the exact condition the setup was meant to prevent. Check the can at every oil change, and more often on a truck that tows or idles heavily.

Installation Notes That Matter

Most 6.7 Cummins CCV reroute kits go on with basic hand tools, but three details separate a setup that works from one that causes pressure problems.

  • Hose size. An undersized vent hose creates crankcase backpressure and defeats the purpose of the modification. Use a hose in the size your kit specifies, and do not neck the vent line down.
  • Routing slope. Route the hose with a continuous downward slope to the exit. Any low spot in the line will collect condensed oil and water. Once that pooled fluid fills the low spot, it blocks the vent and crankcase pressure rises against it.
  • Keep the port capped and secure. When the factory hose comes off the intake horn, that port sits upstream of the turbo, behind the air filter. The block-off plug has to be seated correctly and checked periodically. If it works loose, the turbo pulls unfiltered air, and airborne dust and silica going through the compressor wheel damages it. This is known as turbo dusting, and it is a far more expensive failure than the oil film you were trying to stop.

Follow the instructions that come with your kit. Routing and hardware differ by make and model.

Cold Weather Is the Highest-Risk Condition

Winter operation is where open vent setups cause real damage, and it is documented at the manufacturer level. Cummins TSB140017 addresses crankcase breather and tube freezing on B6.7, ISB, and L9 engines: oil leaks and high crankcase pressure fault codes caused by breather tube icing below freezing. The fix is a cold-weather upfit kit with heaters and a revised breather tube.

Blow-by is rich in water vapor, a normal byproduct of combustion. In a factory system those vapors stay hot because they are pulled straight back into the intake. In a vented reroute they travel through a long hose in ambient air, where they condense and, below freezing, can freeze inside the line. The coldest point is usually the vent tip, which is also the point most likely to ice over first. Once the vent is blocked, crankcase pressure builds with nowhere to go, and the pressure escapes past the weakest seal.

If you run an open vent setup in a cold climate, check the vent tip and the low points of the hose regularly through the winter. A frozen line is a failure that shows up without warning.

Does a Reroute Need a Tune?

A CCV reroute is a mechanical change to the ventilation circuit. It does not change fuel or air calibration.

The catch is the sensor. Depending on model year, the crankcase ventilation circuit is monitored, and some kits require the factory sensor to stay plugged in or to be handled a specific way. If the sensor logic is left unsatisfied, the truck can set crankcase-related codes and a check engine light. Confirm how your kit handles this before you install, and check what your specific year requires.

Some emissions-related modifications do require tuning to address check engine lights, diagnostic codes, or engine calibration.

Removing emissions hardware will require it. For off-road builds, compare 2013 to 2024 Cummins tuner options. The CCV reroute itself is a different case, but confirm the sensor requirement for your truck.

The Legal Status of a CCV Reroute

This is the part that decides whether a reroute is even an option for your truck.

Federal. The Clean Air Act prohibits removing or rendering inoperative any emissions control device installed on a vehicle, and it prohibits manufacturing, selling, or installing parts whose principal effect is to bypass those controls. EPA enforcement documents use the term "crankcase ventilation delete hardware" for aftermarket hardware designed to replace the stock crankcase emission control, and treat it alongside EGR delete kits and delete pipes. A reroute that vents crankcase vapor to atmosphere, or that removes the factory filter element from the circuit, falls under that description. Civil penalties are assessed per vehicle or per device.

California and adopting states. CARB requires an Executive Order for any add-on part that can affect emissions on an emissions-controlled vehicle used on public highways. An EO is a state-issued exemption backed by testing that shows the part does not increase emissions above the factory baseline. A vent-to-atmosphere setup has no path to an EO, because it vents untreated hydrocarbons. A closed-loop catch can could qualify in principle, but only if that specific part carries a valid EO number. Diesel vehicles have been part of California's Smog Check program since January 1, 2010, and the inspection includes a visual check for non-approved aftermarket parts.

One more point worth knowing: a "race use only" or "off-road use only" label does not change how a certified vehicle is treated. CARB Enforcement Advisory 292 states that a violation can occur regardless of the seller's or buyer's claimed intent for how the part will be used.

Reroute and catch-can products are intended only for off-road, race, or non-public-road use where permitted. Check federal, state, and local laws before purchase.

Servicing the Factory System First

If your truck is driven on public roads, a better route to a dry intake is usually to keep the factory system healthy rather than remove it.

  • Replace the CCV filter element at the factory interval. 67,500 miles on 2007.5 to 2018 trucks, 75,000 miles on 2019 and newer, and sooner if the truck tows hard, idles a lot, or runs in dust.
  • Reset the Perform Service message after the filter goes in, using the pedal sequence above.
  • Check the EGR side on 2007.5 to 2012 trucks. The Ram diesel supplement lists EGR valve and EGR cooler cleaning at the same interval as the CCV filter, and carbon buildup on that side is a separate source of intake restriction.
  • Address oil consumption and blow-by causes before assuming the CCV is the problem. Worn rings, a cracked piston, or a failing turbo seal will keep pushing oil no matter what ventilation setup you run.

A healthy filter element and the correct interval solve most of the oil-in-the-intake complaints that send owners shopping for a reroute. For an early truck, see our breakdown of 2007.5 to 2009 6.7 Cummins reliability.

FAQs

How often should I replace the factory CCV filter element?

Follow the factory interval: 67,500 miles for 2007.5 to 2018 Ram 2500 and 3500 trucks, and 75,000 miles for 2019 and newer. Shorten it if the truck tows heavy, idles for long periods, or operates in dusty conditions. The housing is sealed, so you cannot judge saturation by looking at the outside.

How do I reset the Perform Service message after changing the CCV filter?

Turn the ignition to ON/RUN without starting the engine, press and release the brake pedal twice, fully depress and slowly release the accelerator pedal twice within 10 seconds, then turn the ignition to OFF/LOCK. Repeat if the message returns on the next start.

Does a CCV reroute need a tuner?

A reroute does not change fuel or air calibration, so it does not need one for its own sake. Depending on model year, the crankcase ventilation circuit is monitored, and some kits require the factory sensor to stay connected to avoid codes. Confirm the requirement for your truck's year before installing.

Can I run a catch can and stay legal?

That depends on where the truck is registered. A vent-to-atmosphere setup vents untreated vapor and has no path to a CARB Executive Order. A closed-loop catch can could qualify, but only if that specific part carries a valid EO number, and federal anti-tampering rules still apply to the crankcase ventilation circuit. Check federal, state, and local laws before purchase.

What is the best CCV setup for a 6.7 Cummins used for heavy towing?

For a truck that tows near capacity, the practical answer is a healthy factory system on a shortened service interval. Heavy towing produces more blow-by and more oil mist, so the filter element works harder and saturates sooner. If you are running a reroute off public roads, a catch can with real coalescing media handles more throughput than a plain vent, but it needs a drain schedule you will actually keep, because a full reservoir blocks the vent.

Will a CCV reroute stop oil from reaching the intercooler?

It stops crankcase vapor from carrying oil into the intake, which is the main source of that film. It does not fix oil entering the intake from a failing turbo seal, and it does not fix the engine wear that produces excess blow-by in the first place. Diagnose first.

Reroute Kits for Your Cummins

If you run your truck off public roads and want to compare setups, start with our Cummins CCV reroute collection, and read the catch can vs CCV reroute comparison before you decide which configuration fits how you use the truck. The CCV reroute kit buyer's guide covers what each kit includes and what you still need, and the full CCV reroute kit collection covers Cummins, Power Stroke, and Duramax applications.

Not sure what your year needs? Send us your year, model, engine, cab and bed configuration, current crankcase ventilation setup, and any prior modifications. EngineGo support will help you confirm what fits before you order.