Camshaft Position Sensor Implausible
What does DD-636-2 mean?
The DD-636-2 (Detroit Diesel DD Series) diesel fault code means: Camshaft Position Sensor Implausible. This is a moderate severity code.
Common Symptoms
- Check Engine Light / Amber Warning Lamp illuminated
- Rough idle or misfire
- Hard starting or extended crank
Probable Causes (Ranked by Likelihood)
- Failed CMP sensor Very Likely
- Harness fault Possible
Step-by-Step Diagnostic Procedure
Scope CMP during crank.
Check for metal debris on sensor tip.
Replace sensor.
Frequently Asked Questions
What is Detroit Diesel fault code DD-636-2?
Detroit Diesel fault DD-636-2 (SPN 636 FMI 2) indicates: Camshaft Position Sensor 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-636-2?
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-636-2?
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.