Error "F1 Sensor" -- Which Sensor is This?

[radargeek]

With the ALP powered on and not muted, put your hand up to each front sensor to see if it causes the ALP to beep. The sensor that doesn't cause beeps is the one that's failed (and presumably, plugged into the F1 port on the CPU).

If all 3 sensors in front cause beeps, check the rears just in case you have them mixed up. If all 5 sensors cause beeps, disconnect the sensor from the F1 port on the CPU and repeat the test. The sensor that no longer causes beeps is the one on F1.

If none cause beeps, make sure it's not muted and you didn't disable parking sensors in the configuration.