Conditions for Running the DTC

DTC P0641 and P0651 are not set.
The Ignition 1 Signal parameter is more than 11 volts.
The engine is running.
The EGR command will be disabled if the Start-up ECT parameter is less than 5°C (41°F) and will not enable until the ECT Sensor parameter is more than 75°C (167°F)
The DTC P0401 intrusive test is not active.
The EGR valve is not being commanded with a scan tool.
DTC P0406 runs continuously once the above conditions are met.