P1891 – BMW DTC

BMW DTC P1891 – System Voltage High

DTC P1891 meaning on BMW

DTC P1891 on a BMW indicates that the system voltage is higher than normal. This diagnostic trouble code is triggered when the powertrain control module (PCM) detects that the voltage in the vehicle’s electrical system is exceeding the specified limit.

BMW DTC P1891 symptoms

Symptoms of DTC P1891 in a BMW may include:

• Check Engine Light (CEL) illuminated on the dashboard
• Vehicle may experience electrical issues
• Possible battery overcharging

BMW DTC P1891 causes

The common causes of DTC P1891 on a BMW are:

• Faulty alternator
• Defective voltage regulator
• Short circuit in the electrical system
• Issues with the battery

BMW DTC P1891 seriousness

DTC P1891 should not be ignored as it can lead to potential damage to the vehicle’s electrical components. If left unresolved, it may result in further issues with the charging system and other electrical systems in the vehicle.

How to diagnose DTC P1891 on BMW

To diagnose DTC P1891 on a BMW, a mechanic would typically perform the following steps:

1. Use a diagnostic scanner to retrieve the fault codes
2. Check the voltage output of the alternator
3. Inspect the battery and charging system components for any visible damage
4. Test the voltage regulator for proper functioning

How to fix DTC P1891 on BMW

To fix DTC P1891 on a BMW, the following steps may be taken:

1. Replace the alternator if it is found to be faulty
2. Repair or replace the voltage regulator if necessary
3. Check and repair any short circuits in the electrical system
4. Ensure the battery is in good condition and holding a charge

How to erase DTC P1891 on BMW

To erase DTC P1891 on a BMW, the fault code can be cleared using a diagnostic scanner. After the necessary repairs have been made to address the high system voltage issue, the code can be cleared to reset the Check Engine Light and ensure that the problem has been resolved.

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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