BMW DTC P077B – Output Shaft Speed Sensor Circuit – Direction Error
DTC P077B meaning on BMW
DTC P077B refers to an Output Shaft Speed Sensor Circuit – Direction Error detected in a BMW vehicle. This fault code indicates that there is an issue with the output shaft speed sensor circuit, specifically related to the direction error signal.
BMW DTC P077B symptoms
Symptoms of DTC P077B in a BMW may include erratic shifting behavior, transmission slipping, harsh shifting, or the transmission going into limp mode. The vehicle’s transmission may also fail to engage properly or exhibit delayed engagement.
BMW DTC P077B causes
The causes of DTC P077B on a BMW can vary, but common reasons include a faulty output shaft speed sensor, damaged wiring or connectors in the sensor circuit, or issues with the transmission control module (TCM). Additionally, low transmission fluid levels or contaminated fluid can also trigger this fault code.
BMW DTC P077B seriousness
DTC P077B should be addressed promptly as it can lead to further transmission problems if left unresolved. Ignoring this fault code may result in transmission damage, drivability issues, and potential safety concerns while driving the vehicle.
How to diagnose DTC P077B on BMW
To diagnose DTC P077B on a BMW, a mechanic would typically start by using a diagnostic scanner to retrieve the fault code and perform a thorough inspection of the output shaft speed sensor and its circuit. They may test the sensor’s resistance, check for wiring continuity, and inspect the sensor’s connector for any signs of damage or corrosion.
How to fix DTC P077B on BMW
Fixing DTC P077B on a BMW often involves replacing the faulty output shaft speed sensor, repairing any damaged wiring or connectors, and ensuring the transmission fluid is at the correct level and in good condition. In some cases, reprogramming the TCM or performing a software update may be necessary to address the direction error signal.
How to erase DTC P077B on BMW
Once the underlying issue causing DTC P077B has been resolved, the fault code can be cleared using a diagnostic scanner. By erasing the code, the vehicle’s onboard computer will reset the transmission system’s adaptive values and monitor the sensor circuit for any recurring faults.
Recommended tools & DTC Scanners for BMW
Best Diagnostic App for modern BMWs: BimmerLink
Recommended Bluetooth adapter for Bimmerlink: OBDLink CX
Cable adapter for Bimmerlink: Enet Cable USB Type C
For older BMWs we recommend: Autel AutoLink AL319 (2024 version)
Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter
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