It's the connector's they need cleaning. Especially the throttle pedal connector, I know Fiesta/Fusion had an issue with this until 2006.5my when they changed the plug pins and pedal to gold connectors as the Air Con can cause condensation in the connectors.
For a split second you get a miss-connection which throws the lights up then it re-connects and shuts them off again.
Certain faults are given priority (safety critical parts etc etc).
Some components need to be faulty once to put the lamp up
Some need five driving cycles (key out-key in)
Some need twelve.
Some put codes up as a notification that there WAS an issue, whereas some are live.
You need to disconnect the battery earth (-) terminal and disconnect and clean/spray the following connectors AND ports:
then re-connect the battery.
Failing that then the motor is on the way out on the throttle body.
2011 Focus 3-door Zetec 1.6 TDCi.
s - 2006 Panther Black & 2007 Red. Gone and quite forgotten