What Does This Error Mean?

Marlin Z probe failure is almost always caused by the Z_PROBE_OFFSET set too high or low, keeping the probe from reaching the bed, or the probe wiring causing a false trigger. Adjust the probe offset and verify the wiring is not creating electrical noise.

Affected Models

Marlin printers with BLTouch
Marlin printers with CR Touch
Marlin printers with inductive probes
Creality Ender 3 with ABL sensor

Common Causes

Z_PROBE_OFFSET_FROM_EXTRUDER set incorrectly — probe cannot physically reach the bed
BLTouch pin not deploying or retracting reliably due to a dirty tip or worn solenoid
Probe wiring picking up electrical noise from stepper drivers, causing false triggers
Bed physically too far from the probe travel range — Z axis needs manual adjustment
PROBE_OFFSET_FROM_EXTRUDER sign wrong — positive when it should be negative or vice versa

How to Fix It

Manually home the Z axis and verify probe reach.

Home the printer (G28) and then send G29 to begin bed leveling. Watch whether the probe actually deploys and descends to the bed surface. If the probe never touches the bed, the nozzle is physically too far above the bed — manually lower the Z axis by turning the lead screw or adjusting the Z stop position.
Check and correct the probe Z offset.

The Z offset tells Marlin the distance between the probe trigger point and the nozzle tip. Send M851 to check the current value. Adjust using M851 Z-2.0 (for example) and save with M500. The offset is negative when the nozzle is below the probe trigger point, which is the most common configuration.
Test the BLTouch or CR Touch manually.

Send M280 P0 S10 to deploy the pin and M280 P0 S90 to retract it. If the pin does not move, the servo inside the probe is faulty. If the pin deploys but does not retract, the tip may be dirty or bent — clean the pin with isopropyl alcohol and check it for bending.
Check probe wiring for electrical noise.

Route the probe signal wire away from stepper motor cables, which generate electrical interference. Use a shielded cable for the probe signal wire if noise is suspected. Electrical noise from unshielded routing near steppers causes phantom false triggers that Marlin reports as Probe Triggered Early.
Verify MULTIPLE_PROBING is enabled.

In Configuration.h, set MULTIPLE_PROBING to 2 or 3. This causes Marlin to probe each point multiple times and take the average, filtering out single false triggers. Even one false trigger in a single-probe configuration causes an immediate probe failure error.

When to Call a Professional

BLTouch and CR Touch units are user-replaceable. If the probe pin is bent or the solenoid does not respond to deploy/retract commands (M280), replace the probe unit.