DPF Inlet Temperature Implausible
What does DD-3609-2 mean?
The DD-3609-2 (Detroit Diesel DD Series) diesel fault code means: DPF Inlet Temperature Implausible. This is a moderate severity code.
Common Symptoms
- Check Engine Light / Amber Warning Lamp illuminated
- DPF regen inhibited or failing
Probable Causes (Ranked by Likelihood)
- Failed DPF inlet temp sensor Likely
- Harness heat damage Possible
Step-by-Step Diagnostic Procedure
Live-data compare upstream temps.
Replace inlet temp sensor.
Frequently Asked Questions
What is Detroit Diesel fault code DD-3609-2?
Detroit Diesel fault DD-3609-2 (SPN 3609 FMI 2) indicates: DPF Inlet Temperature Implausible. It is a moderate-severity fault and is commonly seen on DD13/DD15/DD16 engines in Freightliner and Western Star chassis.
Can I drive my Freightliner or Western Star with fault DD-3609-2?
It depends on severity. Critical and serious faults trigger derate or engine shutdown — do not continue driving. Moderate faults usually allow continued operation short-term but schedule repair to prevent cascading aftertreatment damage.
How much does it cost to fix Detroit Diesel fault DD-3609-2?
Typical repair cost is $500-$2,200. Sensor/harness fixes fall at the low end; turbo actuator, injector, aftertreatment component, or head gasket repairs fall at the high end. Detroit DDDL software and sometimes factory parameter reset are required for proper reset.