BMW DTC P1871 – 2-1 Shift Circuit High
DTC P1871 meaning on BMW
The Diagnostic Trouble Code (DTC) P1871 for BMW refers to a fault in the 2-1 Shift Circuit High. This code indicates that there is an electrical issue related to the transmission’s 2-1 shift operation, specifically a high voltage condition in the circuit.
BMW DTC P1871 symptoms
Symptoms of DTC P1871 on a BMW may include harsh shifting between gears, delayed or erratic shifting, transmission slipping, and in some cases, the transmission may go into a failsafe or limp mode. The Check Engine Light (CEL) may also illuminate on the dashboard.
BMW DTC P1871 causes
The common causes of DTC P1871 on a BMW include faulty wiring or connectors in the 2-1 shift circuit, a malfunctioning transmission control module (TCM), issues with the shift solenoids, or a problem with the transmission itself such as internal damage or wear.
BMW DTC P1871 seriousness
DTC P1871 should be addressed promptly as it can lead to further damage to the transmission if left unresolved. Ignoring this code may result in more severe transmission issues and potentially costly repairs in the future.
How to diagnose DTC P1871 on BMW
To diagnose DTC P1871 on a BMW, a mechanic would typically start by using a diagnostic scanner to retrieve the fault codes stored in the vehicle’s computer. They would then inspect the wiring and connectors in the 2-1 shift circuit, test the shift solenoids, and check the transmission fluid level and condition. Further testing may be required to pinpoint the exact cause of the issue.
How to fix DTC P1871 on BMW
Fixing DTC P1871 on a BMW may involve repairing or replacing any damaged wiring or connectors in the 2-1 shift circuit, addressing any issues with the shift solenoids, or replacing the transmission control module if necessary. In some cases, a transmission fluid flush and filter replacement may also be recommended. It is important to follow the manufacturer’s repair procedures and guidelines when addressing this fault code.
How to erase DTC P1871 on BMW
Once the underlying issue causing DTC P1871 on a BMW has been diagnosed and fixed, the fault code can be cleared using a diagnostic scanner. This will reset the Check Engine Light and erase the code from the vehicle’s computer memory. It is important to ensure that the repair has been successful before clearing the code to prevent it from reoccurring.
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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