Overview
The ZF 4646.125.004 INDUCTIVE SENSOR is a critical electronic component engineered specifically for the WG 251 transmission series. This OEM genuine part monitors rotational speed and position of internal shafts by generating a magnetic field that detects ferrous targets passing through its sensing face. Mounted directly into the TRANSMISSION HOUSING, the sensor transmits real-time data to the transmission control unit (TCU), enabling precise shift timing and clutch modulation. The SKU 4646.125.004 is a direct replacement for the original factory-installed sensor, ensuring seamless integration with existing wiring harnesses and control logic.
Symptoms of Failure
- Erratic or delayed gear engagement — When the 4646.125.004 sensor fails, the TCU loses accurate shaft speed data, causing harsh or delayed shifts, especially during upshifts from 2nd to 3rd gear.
- Intermittent limp mode activation — A failing inductive sensor often triggers fault codes P0715 or P0720, forcing the transmission into a protective limp-home mode with reduced power and locked gear selection.
- No start condition or stalled torque converter — Without proper speed signals from the sensor, the TCU may prevent engine cranking or fail to lock the torque converter, leading to stalling at low speeds.
- Oil contamination from sensor seal breach — A cracked sensor housing allows transmission fluid to leak past the O-ring into the wiring connector, causing intermittent electrical shorts and visible fluid drips near the bell housing.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4646.125.004 |
| Type | Inductive Proximity Sensor (2-wire) |
| Operating Voltage | 10–30 VDC |
| Output Signal | Frequency square wave (0.5–5 kHz) |
| Housing Material | Nickel-plated brass with PTFE seal |
| Thread Size | M18 x 1.5 |
| Overall Length | 62 mm |
| Hex Nut Size | 24 mm |
| Weight | 0.045 kg |
| OEM Reference | ZF 4646.125.004 |
| Operating Temperature | -40°C to +125°C |
| Protection Class | IP67 |
Compatibility
This inductive sensor is a direct fit for the ZF WG 251 series transmissions used in medium-duty trucks, buses, and construction equipment. Based on its thread pattern and electrical characteristics, the 4646.125.004 also cross-references with earlier WG 180 and WG 200 models that share the same sensor bore location in the HOUSING. It is not compatible with Ecomat or AS Tronic series transmissions. Always verify the sensor mounting depth against the COVER clearance before installation. Secure the sensor using a CAP SCREW to prevent vibration loosening.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101072 | TRANSMISSION HOUSING | Main structural casing that houses all internal components |
| 4646301201 | HOUSING | Secondary housing for valve body and sensor mounting |
| 4646301166 | COVER | Seals the sensor cavity and protects wiring |
| 0636101051 | CAP SCREW | Fastens sensor bracket to housing |
| 4646201018 | COVER SHEET | Gasket layer between housing and cover |
| 4646301277 | SCREEN SHEET | Filter mesh for oil return passage |
| 4646201019 | COVER SHEET | Secondary gasket for valve body cover |
| 0730365125 | TYPE PLATE | Identification tag with transmission serial number |
| 0631311009 | GROOVED STUD | Alignment dowel for housing assembly |
| 0636010216 | HEXAGON SCREW | Secures cover plate to transmission housing |
