Common Symptoms
- Check engine light illuminated
- DEF system warning light or message displayed
- Reduced engine power or derate condition
- Increased NOx emissions
- DEF consumption abnormally low or zero
- Failed emissions test
Most Likely Root Causes
- Failed DEF injector solenoid
- Open circuit in DEF injector wiring harness
- Corroded or damaged DEF injector connector
- Failed DEF system control module
- Broken or chafed wiring between control module and injector
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Component Location
The DEF injector is typically mounted on the exhaust system upstream of the SCR catalyst, often near the turbocharger or mid-exhaust section.
Manufacturer Notes
Diesel exhaust fluid systems are highly susceptible to corrosion at electrical connections due to DEF crystallization and environmental exposure.
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