Overview
The ZF 6073.015.173 EST 37 A for BP230 is an OEM genuine solenoid valve assembly engineered specifically for the BP 230 series transmission. This critical electro-hydraulic component modulates oil flow to control clutch and brake application, directly governing shift timing and pressure modulation within the valve body. As a direct replacement for the original factory part, the SKU 6073.015.173 ensures precise signal response and consistent hydraulic regulation. When installed alongside the TRANSMISSION HOUSING, this solenoid restores factory-specified shift quality and prevents erratic gear engagement in heavy-duty applications.
Symptoms of Failure
- Delayed or harsh shifting under load: A failing EST 37 A solenoid causes sluggish engagement between gears, particularly when towing or climbing grades, as hydraulic pressure regulation degrades.
- Intermittent transmission slipping in 3rd and 4th gear: Worn internal coils or stuck valve spools produce momentary loss of clutch pressure, resulting in RPM flare without corresponding acceleration.
- Erratic shift patterns and limp-mode activation: The transmission control unit detects abnormal solenoid resistance or flow, triggering a fail-safe mode that locks the gearbox in a single gear until the part is replaced.
- Visible oil seepage around the valve body connector: Degraded O-rings on the solenoid housing allow ATF to weep past the electrical connector, leaving oily residue on the transmission pan and wiring harness.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number / SKU | 6073.015.173 |
| OEM Reference | ZF EST 37 A for BP230 |
| Material | Hard-anodized aluminum body with stainless steel spool |
| Weight | 0.42 kg (0.93 lbs) |
| Coil Resistance | 5.2 ± 0.3 ohms at 20°C |
| Operating Pressure Range | 3.5 – 18 bar |
| Seal Type | Viton O-ring (included) |
| Thread Size | M12 x 1.5 mounting bore |
Compatibility
This solenoid is designed for the ZF BP 230 series but also fits several related heavy-duty automatic transmissions. Verified compatible models include the WG180, WG200, and WG210 series when equipped with the BP230 valve body configuration. It is also used in certain ZF Ecomat 4HP and 5HP variants that share the EST 37 A solenoid architecture. For proper installation, ensure the HOUS.FRONT SECT and HOUSING REAR PART are free of debris, and verify that the HOUSING REAR SECTION aligns correctly with the solenoid bore to prevent cross-threading.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101078 | TRANSMISSION HOUSING | Main structural casing for gear and valve body assembly |
| 4657201166 | HOUS.FRONT SECT | Front section housing the torque converter and oil pump |
| 4657201168 | HOUSING REAR PART | Rear casing supporting output shaft and governor assembly |
| 4657298101 | HOUSING REAR SECTION | Intermediate housing section for planetary gear sets |
| 0631306816 | CYLINDRICAL PIN | Alignment dowel for housing mating surfaces |
| 0636100801 | CAP SCREW | M10 x 30 hex head bolt for housing fastening |
| 4656301148 | FIXING PLATE | Retaining plate for solenoid valve positioning |
| 4657301032 | SCREEN SHEET | Fine mesh filter for valve body oil gallery |
| 4657301033 | SCREEN SHEET | Coarse mesh pre-filter for main oil circuit |
| 0636100803 | CAP SCREW | M8 x 20 hex head bolt for valve body attachment |
Frequently Asked Questions
Q: Can the 6073.015.173 solenoid be tested before installation?
A: Yes. Measure coil resistance between the two pins; it should read 5.2 ohms. Apply 12V DC briefly to hear an audible click from the spool movement. Do not apply continuous power for more than 2 seconds to avoid overheating.
Q: Will this part fit a ZF WG180 transmission built before 2005?
A: It is compatible with WG180 units that use the BP230 valve body. Check the transmission tag for “BP230” designation. Earlier WG180 models with a BP210 valve body require a different solenoid variant.
Q: What torque specification should be used for the mounting bolt?
A: Tighten the M12 retaining bolt to 25 Nm (18 ft-lbs). Over-torquing can distort the solenoid housing and cause internal binding of the spool valve.
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