Overview
The ZF 4644.125.478 INDUCTIVE SENSOR is a precision electronic component engineered specifically for the WG150 transmission series. This OEM genuine part monitors rotational speed and position of internal shafts by generating a magnetic field that detects ferrous targets without physical contact. Mounted directly into the transmission housing, the sensor relays critical data to the electronic control unit (ECU) to manage shift timing and clutch engagement. The SKU 4644.125.478 ensures exact fitment and OEM-specified signal output, eliminating calibration issues common with aftermarket substitutes. For proper installation, this sensor interfaces with the TRANSMISSION HOUSING (4642101109) and the TRANSMISSION HOUSING (4642301205), both of which provide the sealed mounting bore required for accurate sensing.
Symptoms of Failure
- Erratic gear engagement or delayed shifting – A failing inductive sensor sends intermittent or false speed signals, causing the transmission to hesitate or slam into gears during acceleration.
- Transmission enters limp mode without warning – When the ECU detects no signal from the 4644.125.478, it defaults to a safe mode, limiting vehicle speed to 20-30 mph to prevent internal damage.
- Intermittent loss of reverse gear – Worn sensors often fail to detect reverse shaft rotation, resulting in a no-reverse condition that may appear random.
- Check engine light with speed sensor codes – Diagnostic trouble codes P0720 or P0722 frequently accompany a degraded inductive sensor, indicating output speed signal loss.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.125.478 |
| Type | Inductive Proximity Sensor (2-wire) |
| Operating Voltage | 10–30 VDC |
| Output Signal | Frequency square wave (0–5 kHz) |
| Housing Material | Stainless steel (V2A) |
| Thread Size | M12 x 1.5 |
| Overall Length | 65 mm |
| Weight | 0.045 kg |
| OEM Reference | ZF 4644.125.478 |
| Sealing | IP67 rated with O-ring |
Compatibility
While the 4644.125.478 is primarily designed for the WG150 series, its mounting pattern and signal characteristics make it compatible with several ZF off-highway transmissions. Models that share this sensor include the WG180, WG200, and WG250 series, particularly those built after 2010. The sensor also fits select WG120 and WG160 variants when used with the correct adapter harness. Always verify the TYPE PLATE (0730365125) on your transmission to confirm the exact model variant before ordering. The GROOVED STUD (0631311009) is required to secure the sensor harness in high-vibration applications.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4642101109 | TRANSMISSION HOUSING | Main structural casing for sensor mounting |
| 4642301205 | TRANSMISSION HOUSING | Alternate housing variant for WG150 |
| 0730365125 | TYPE PLATE | Model identification plate for transmission |
| 0631311009 | GROOVED STUD | Secures sensor harness routing |
| 4642301168 | SCREEN SHEET | Oil filter screen for hydraulic circuit |
| 4642301169 | SCREEN SHEET | Fine mesh screen for valve body protection |
| 0636100621 | HEXAGON SCREW | Fastener for sensor bracket |
| 4642301186 | SCREEN SHEET | High-flow screen for cooler return |
| 4644106324 | SHIFT SYSTEM | Electro-hydraulic shift control assembly |
| 4644306598 | PLATE | Mounting plate for sensor harness |
