Common Rail Pressure Regulator Flow Demand High
What does DD-5571-0 mean?
The DD-5571-0 (Detroit Diesel DD Series) diesel fault code means: Common Rail Pressure Regulator Flow Demand High. This is a moderate severity code.
Common Symptoms
- Check Engine Light / Amber Warning Lamp illuminated
- Noticeable power loss under load
- Hard starting or extended crank
Probable Causes (Ranked by Likelihood)
- Failing HPFP Likely
- Internal rail leak (injector) Likely
- Regulator stuck open Possible
Step-by-Step Diagnostic Procedure
Injector return flow test to isolate leaking injector.
Measure HPFP output.
Replace rail pressure regulator if isolated.
Frequently Asked Questions
What is Detroit Diesel fault code DD-5571-0?
Detroit Diesel fault DD-5571-0 (SPN 5571 FMI 0) indicates: Common Rail Pressure Regulator Flow Demand 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-5571-0?
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-5571-0?
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.