Code result
P20FF
Reductant Control Module Performance
Moderate severity
What it means
The dedicated SCR/reductant control module reports an internal performance fault — failed self-tests, watchdog resets, or calibration mismatch. Frequently a forerunner of total module failure.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Internal module fault
highOne of the most commonly reported causes for this code — check this first.
Calibration mismatch after software update
mediumA plausible cause — test and verify before replacing parts.
Module software outdated, reflash may resolve
lowLess common, but worth ruling out after the more likely causes.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P20FF freeNo credit card required