on a Nissan?

Both lights pointing up indicates the system "thinks" the nose is low, so it would point to a sensor problem... depends on how many sensors and where they are ..

usually if the socket falls out of the back of the sensor on the suspension arm, "headlight field of vision" is shown on the display and the lights default to their lowest setting. If lights are high, sounds like the sensor itself is intact but not connected to the suspension arm. Possibly one of the small rose joints has broken either end of the small, once chrome but now probably rusty, connector rod.

Basically, check both suspension arm sensors are in tact and connected from chassis to suspension. Both sensors can be seen between door and wheel front and back on the suspension arms. May help to turn the front wheels to right full lock. Remove for access.

... Just to add, there is a calibration function accessible by Tech 2. I think this just zeroes the indications from the sensors on the assumption that the car is level and is probably used when a sensor is changed. Might be worth a try just in case the ECU has got itself in a muddle. Check the sensors and clean the connectors first though.

Kevin