4197240C93 | Genuine International® Tank Def 7 Gal Blow Molded Assy

• Stores DEF (Diesel Exhaust Fluid)

• Keeps it usable (heats it when frozen, monitors quality)

• Supplies the right amount to the exhaust system at the right time

Modern diesel engines use a system called SCR (Selective Catalytic Reduction). In that system:

• DEF is injected into the exhaust

• It reacts with exhaust gases

• Converts nitrogen oxides (NOx) — nasty pollutants — into harmless nitrogen and water vapor

The assembly makes the system reliable by:

• Preventing frozen DEF from stopping the vehicle

• Making sure DEF isn’t contaminated or diluted

• Letting the computer know DEF level and system health

• Triggering warnings or speed limits if something’s wrong

• DEF warning light or Check Engine Light

• Messages like:

  • “Service DEF System”

  • “Poor DEF Quality”

  • “No Engine Start in XXX Miles”

Cold-weather problems

• Warning shows up only when it’s cold

• DEF heater failure codes

• Vehicle won’t dose DEF until it warms up

DEF level acts weird

• Gauge stuck on full or empty

• DEF level doesn’t change even after refilling

• Countdown continues after adding DEF

Power or drivability issues

• Reduced power / limp mode

• Speed limited (sometimes 5–55 mph max)

• Vehicle eventually won’t start

Emissions / sensor faults

• “Poor DEF quality” even with fresh DEF

• Failed temperature, quality, or level sensors

• SCR efficiency or NOx-related fault codes

Leaks or crystallization

• White, chalky residue under the truck

• DEF smell (ammonia-like)

• Visible leaks near the tank or lines

Common causes

• Internal heater failure

• Corroded wiring inside the tank

• Bad pump/supply module

• Contaminated DEF