BMW DTC P1801 – Shift Solenoid ‘A’ Circuit Low
DTC P1801 meaning on BMW
DTC P1801 indicates a fault with the Shift Solenoid ‘A’ Circuit in a BMW vehicle. This fault code is triggered when the Powertrain Control Module (PCM) detects that the voltage signal from the shift solenoid ‘A’ is lower than the specified range.
BMW DTC P1801 symptoms
Symptoms of DTC P1801 in a BMW may include harsh shifting, delayed shifting, transmission slipping, or the transmission may fail to shift at all. The vehicle may also experience decreased fuel efficiency and overall performance issues.
BMW DTC P1801 causes
The common causes of DTC P1801 in a BMW include a faulty shift solenoid ‘A’, damaged wiring or connectors in the shift solenoid circuit, low transmission fluid level, or a malfunctioning PCM.
BMW DTC P1801 seriousness
DTC P1801 should be addressed promptly as it can lead to further damage to the transmission system if left unresolved. Ignoring this fault code may result in more severe transmission issues and potentially costly repairs.
How to diagnose DTC P1801 on BMW
To diagnose DTC P1801 on a BMW, a mechanic would typically start by using a diagnostic scanner to retrieve the fault codes stored in the PCM. They would then inspect the shift solenoid ‘A’ and its circuit for any visible damage or loose connections. Testing the solenoid’s resistance and checking the transmission fluid level may also be necessary.
How to fix DTC P1801 on BMW
Fixing DTC P1801 on a BMW usually involves replacing the faulty shift solenoid ‘A’ and repairing any damaged wiring or connectors in the circuit. Ensuring the transmission fluid is at the correct level and in good condition is also important. In some cases, reprogramming or replacing the PCM may be necessary.
How to erase DTC P1801 on BMW
Once the underlying issue causing DTC P1801 has been resolved, the fault code can be cleared using a diagnostic scanner. This will reset the PCM and turn off the Check Engine Light. It is important to verify that the repair was successful by driving the vehicle and rescanning for any remaining fault codes.
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
Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.