Overview
The ZF 4646.125.002 INDUCTIVE SENSOR is a precision electronic component engineered for the WG250 and WG251 transmission series. This OEM genuine part monitors rotational speed and position within the gearbox, sending critical data to the transmission control unit (TCU) to ensure precise shift timing and clutch engagement. Mounted directly into the TRANSMISSION HOUSING, the sensor detects ferrous targets on rotating shafts without physical contact, eliminating wear from friction. The SKU 4646.125.002 is a direct replacement for factory-installed units, guaranteeing identical signal output and mechanical fitment for ZF off-highway and industrial transmissions.
Symptoms of Failure
- Erratic gear engagement or delayed shifting: When the inductive sensor fails, the TCU receives inconsistent speed data, causing harsh or delayed shifts, especially under load.
- Transmission stuck in limp mode: A faulty 4646.125.002 often triggers a fault code that forces the transmission into a reduced-power safety mode, limiting vehicle speed to 20-30 km/h.
- Intermittent loss of reverse gear: Worn sensors can cause the TCU to misinterpret shaft rotation, leading to sudden loss of reverse function during low-speed maneuvering.
- No start condition with active warning light: A completely failed sensor prevents the TCU from confirming neutral position, blocking engine cranking and illuminating the transmission warning lamp.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4646.125.002 |
| Sensor Type | Inductive proximity (2-wire) |
| Operating Voltage | 10-30 VDC |
| Output Signal | Digital square wave (NPN) |
| Housing Material | Stainless steel (V2A) |
| Thread Size | M12 x 1.5 |
| Overall Length | 55 mm |
| Hexagon Flats | 18 mm |
| Weight | 0.04 kg |
| OEM Reference | ZF 4646.125.002 |
| Sealing | O-ring (included) |
| Protection Class | IP67 |
Compatibility
This inductive sensor is primarily designed for the ZF WG250 and WG251 series, but its mounting pattern and electrical characteristics also suit the WG180, WG200, and WG210 transmissions used in construction loaders, forklifts, and agricultural tractors. The sensor interfaces directly with the HOUSING assembly and is secured by a HEXAGON SCREW (M6 x 20 mm). For full access during replacement, the COVER must be removed from the transmission side. Always verify the sensor gap (0.8-1.2 mm) to the target wheel after installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101028 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4646301095 | HOUSING | Sensor mounting bracket and oil channel |
| 4646301087 | COVER | Access plate for sensor and valve block |
| 0636015304 | HEXAGON SCREW | Fastener for sensor retaining bracket |
| 0636101828 | CAP SCREW | Bolt for cover plate attachment |
| 4646301102 | COVER SHEET | Thin gasket for oil sealing |
| 4646301098 | COVER SHEET | Secondary sealing shim |
| 0730365125 | TYPE PLATE | Identification tag for transmission model |
| 0631311009 | GROOVED STUD | Alignment pin for housing assembly |
| 0636101193 | CAP SCREW | Fastener for valve body attachment |
