No.: 13 TS-17
May 31, 2013
TO:

Service Locations

FROM:

Service Operations

SUBJECT:

EPA10/GHG14 Diesel Exhaust Fluid (DEF) in Fuel System/Diesel Fuel in DEF
System Contamination

ISSUE
Major fuel system damage can occur when DEF is introduced into the fuel system. A no-start condition,
engine overspeed, or engine ran backwards complaints can all be caused by DEF in the fuel system.
DEF system damage can occur when diesel fuel is introduced into the DEF system. DEF quality fault
codes (SPN 3364) and NOx conversion fault codes (SPN 4364) can be caused by diesel fuel in the
DEF system.
CAUSE
DEF in the fuel system is caused by accidentally adding DEF to the fuel tank. DEF is about 70% water
and is not combustible. The high water content in DEF can cause corrosion and major fuel system and
fuel injector damage.
Likewise, diesel fuel in the DEF system is caused by accidentally adding diesel fuel to the DEF tank.
The hydrocarbons in the diesel fuel can cause seal failure in the various components of the
DEF system.
Possible Symptoms for DEF in the Fuel System:
• Rust deposits
• Crystallization on fuel filters and fuel module
• Strong ammonia smell from fuel filters and fuel module
• Higher separation in fuel sample

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REQUIRED ACTION
1. If DEF in the diesel fuel is suspected, ask the owner and/or driver when DEF was last
added to the truck. If DEF was recently added, it is possible that DEF was accidently
added to the fuel tank.
2. Because DEF is about 70% water, the best place to check is the fuel filter module. Drain
the water bowl into a clear container.
3. Next remove the fuel filters from the fuel filter module and the frame mounted housing (if
equipped). Place the fuel filters on a clean work bench. Do not reinstall the fuel filter
caps on the fuel filter module.
4. Observe the smell of the fuel filters and the fuel in the fuel filter module. DEF has a
strong ammonia smell.
5. Inspect the inside of the fuel filter module for rust deposits.
6. Place a shop towel over the openings of the fuel filter module and frame mounted
housing (if equipped) to prevent any dust collection.
7. Allow the fuel filters and fuel filter module to sit for one hour.
8. After one hour of sitting, inspect the fuel filters and fuel filter module for crystallization.
Crystallization can be dark brown, light brown, or white in color. If crystallization is found,
the fuel system is contaminated with DEF. See Figures 1 and 2.

Frame Mounted Filter (if equipped)

Engine Mounted Filter

Figure 1 – Examples of Fuel Filters Contaminated with DEF

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Figure 2 – Examples of Fuel Filter Modules Contaminated with DEF

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Inspect the fuel sample that was drained from the water bowl. DEF and water are
heavier then fuel and will settle to the bottom of the sample. It is possible a small
amount of water and sediment will be in the sample. See Figure 3.

Possible Indicator of DEF In Fuel
Figure 3 – Fuel Samples

ADDITIONAL INFORMATION
Fuel samples pulled from fuel tanks have proven to be ineffective in determining DEF in fuel
related failures. DEF and diesel fuel do not mix. Because DEF is heavier than fuel, the DEF is
pulled into the engine when it is running. The water separator/coalescer system in the fuel filter
module is designed to handle a normal amount of water accumulation in diesel fuel, mainly from
condensation and fuel handling. When DEF is added to the fuel tanks, this is usually a larger
quantity (2.5 gal +). Because this liquid would be drawn into the fuel filter module at one time,
the water separator/coalescer cannot effectively separate the DEF from the fuel at this rate. A
small amount of DEF will then be trapped in the fuel filter module and some will pass through to
the fuel system potentially causing damage. It is possible to have a "DEF in fuel" failure and find
no evidence of DEF in the fuel tank(s). It is also possible for fuel pulled from tanks to show no
DEF in a Fuel Analysis. If fuel tank samples are taken, they must be taken from the bottom of
the fuel tank by using the bottom drain (if equipped) or suitable siphon equipment that can reach
the bottom of the tank.
REQUIRED MATERIAL
For DEF in the fuel system failure, replace the following parts.
• Amplifier and Needle Return Lines
• Frame Mounted Fuel Filter (If Equipped)
• Fuel Filter Module
• Fuel Injectors
• Fuel Rail
• High Pressure Fuel Injector Lines
• High Pressure Fuel Pump
• High Pressure Fuel Rail Feed Lines

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For diesel fuel in the DEF system failure, table 1 provides a list of parts that must be replaced.
Part Description
DEF Tank
DEF Tank Header
DEF Supply Line From DEF Tank To DEF Pump
DEF Return Line From DEF Pump To DEF Tank
DEF Line From DEF Pump To DEF Metering Unit
DEF Line From DEF Pump To DEF Dosing Unit
DEF Return Line From DEF Dosing Unit To DEF Tank
DEF Pump
DEF Metering Unit
Aerosol Line From DEF Metering Unit To DEF Nozzle
DEF Dosing Unit

Comments
Chassis OEM Part
Chassis OEM Part
Chassis OEM Part
EPA10 Only, Chassis OEM Part
EPA10 Only, Chassis OEM Part
GHG14 Only, Chassis OEM Part
GHG14 Only, Chassis OEM Part
Detroit Diesel Part
EPA10 Only, Detroit Diesel Part
EPA10 Only, Detroit Diesel Part
GHG14 Only, Detroit Diesel Part

Table 1 – Parts to be Replaced for Diesel Fuel in the DEF System

REPAIR PROCEDURE
If DEF is found in the fuel, replace the appropriate parts shown above. Reference the
EPA07/10/GHG14 Fuel Manual (DDC-SVC-MAN-0082) for proper repair procedures. All OEM
fuel lines should be cleaned or replaced if found corroded or damaged. Fuel tanks should be
drained of the contaminated fuel, and the fuel disposed per Federal, State, and local rules.
If fuel is found in the DEF system, replace the appropriate parts shown above. Reference the
EPA07/10/GHG14 Exhaust – EGR - ATS Manual (DDC-SVC-MAN-0083) for proper repair
procedures.

CLAIM PROCESS
DEF in the fuel system or fuel in the DEF system are not warrantable failures. Any failures that
occur to fuel system components as a result of DEF in the fuel system will not be covered under
warranty or extended coverage (if any).
CONTACT INFORMATION
Please contact the Detroit Customer Support Center at 800-445-1980 or email
[email protected] if you have any questions.