BMW 840Ci transmission failsafe warning and engine stall issue with suspected throttle position sensor failure on BMW 840Ci

Submitted by Vehicle Owner · Jun 23, 2025
Published by RepairPal

Problem overview

Some BMW 840Ci owners report experiencing a transmission failsafe warning, often indicated by the "Trans. Failsafe Prog" message, which may arise from issues such as low transmission fluid, low voltage, or a faulty alternator. These warnings can signal potential threats to the transmission's proper functioning. Additionally, some owners encounter engine stalls alongside the transmission failsafe warning, suggesting deeper systemic problems, possibly linked to the battery or alternator. A suspected throttle position sensor failure is also reported, as this component is vital for regulating air intake and its malfunction can lead to erratic engine behavior, including stalling. To address these concerns, owners are advised to check the throttle position sensor, inspect the battery and alternator, and consider consulting a BMW specialist for accurate diagnostics. Regular maintenance, including timely servicing of fluids, is emphasized to prevent more severe issues stemming from ignored warning signs.

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