EGR Position Sensor Circuit High
What does DD-27-3 mean?
The DD-27-3 (Detroit Diesel DD Series) diesel fault code means: EGR Position Sensor Circuit High. This is a moderate severity code.
Common Symptoms
- Check Engine Light / Amber Warning Lamp illuminated
- EGR valve not tracking command
Probable Causes (Ranked by Likelihood)
- Open 5V reference to EGR position sensor Likely
- Shorted signal wire to voltage Likely
- EGR valve/sensor assembly internal fault Possible
Step-by-Step Diagnostic Procedure
Back-probe EGR position sensor — expect ~0.5V closed, ~4.5V open.
Verify 5V reference on the sensor connector key-on, engine off.
Check signal wire for short to battery or other 5V circuits.
Replace the EGR valve assembly if sensor is integrated.
Clear code and retest after short drive cycle.
Frequently Asked Questions
What is Detroit Diesel fault code DD-27-3?
Detroit Diesel fault DD-27-3 (SPN 27 FMI 3) indicates: EGR Position Sensor Circuit High. 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-27-3?
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-27-3?
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.