The ZF 8HP50, including BMW-designated GA8HP50Z and GA8HP50X versions, is a second-generation 8-speed electronically controlled automatic transmission developed for longitudinal-engine applications. It uses a hydrodynamic torque converter with lock-up clutch, four planetary gearsets and five shift elements to provide eight forward ratios. Designed as the successor to the lower-torque 8HP45, the 8HP50 provides improved efficiency and is rated for approximately 500 Nm of input torque.
Specification: 8-speed automatic • ZF 8HP50 • BMW GA8HP50Z / GA8HP50X • Longitudinal installation • Rear-wheel-drive and all-wheel-drive applications • GA8HP50Z primarily rear-wheel drive • GA8HP50X xDrive/AWD • Torque converter with lock-up clutch • Four planetary gearsets • Five shift elements • Integrated electro-hydraulic mechatronic control • Adaptive shift control • Approximately 500 Nm maximum input torque • ZF LifeguardFluid 8 on applicable versions • Multiple application-specific transmission and mechatronic variants.
The 8HP50 family is fitted extensively across selected BMW 1-Series, 2-Series, 3-Series, 4-Series, 5-Series and X-series applications, with related versions used by other manufacturers. BMW commonly identifies rear-wheel-drive units as GA8HP50Z and xDrive versions as GA8HP50X. Components vary by vehicle, engine, drivetrain and production date, so the VIN, complete ZF transmission number and individual component identification should always be confirmed before ordering replacement parts.
Common Faults
Common 8HP50 problems include valve-body and mechatronic faults, hydraulic pressure or solenoid problems, torque-converter lock-up wear, adaptation/software issues and internal clutch wear. Symptoms can include harsh or delayed shifts, shift flare, slipping, incorrect or missing gears, converter judder, transmission warnings and failsafe operation.
Accurate hydraulic pressure and clutch adaptation are critical to 8HP operation, so valve-body wear, fluid loss or incorrect adaptations can cause significant shift problems without necessarily indicating major internal failure. Diagnosis should include fault codes, adaptation values, hydraulic operation and fluid condition before internal components are replaced.
Common Fault Codes
| Fault Code | Description |
|---|---|
| P0700 | Transmission control system fault / additional TCM faults stored |
| P0711 | Transmission fluid temperature sensor range / performance fault |
| P0715 | Input / turbine speed sensor circuit fault |
| P0716 | Input / turbine speed sensor range / performance fault |
| P0720 | Output speed sensor circuit fault |
| P0721 | Output speed sensor range / performance fault |
| P0730 | Incorrect transmission gear ratio |
| P0731 | Incorrect 1st gear ratio |
| P0732 | Incorrect 2nd gear ratio |
| P0733 | Incorrect 3rd gear ratio |
| P0734 | Incorrect 4th gear ratio |
| P0741 | Torque converter clutch performance / lock-up fault |
| P0742 | Torque converter clutch stuck on |
| P0868 | Transmission fluid / line pressure too low |
| U0101 | Lost communication with transmission control module |