BMW DTC P3121 – Cylinder 6 High Pressure Injector Low Side Circuit Low
DTC P3121 meaning on BMW
The DTC P3121 on a BMW indicates an issue with the Cylinder 6 High-Pressure Injector Low Side Circuit being detected as having low voltage. This fault code is specific to the fuel injector for cylinder 6 in the high-pressure fuel system.
BMW DTC P3121 symptoms
Symptoms of the DTC P3121 on a BMW may include rough idling, misfires, loss of power, decreased fuel efficiency, and potentially an illuminated check engine light on the dashboard.
BMW DTC P3121 causes
The common causes of the DTC P3121 on a BMW include a faulty high-pressure fuel injector, wiring issues in the injector circuit, poor electrical connections, or a problem with the Engine Control Module (ECM).
BMW DTC P3121 seriousness
The seriousness of the DTC P3121 on a BMW lies in the potential drivability issues it can cause, such as rough running and decreased engine performance. Ignoring this fault code can lead to further damage to the engine and catalytic converter.
How to diagnose DTC P3121 on BMW
To diagnose the DTC P3121 on a BMW, a mechanic would typically perform a visual inspection of the injector and its wiring, conduct electrical tests to check for voltage and continuity, and use a diagnostic scanner to retrieve specific fault code information from the ECM.
- Inspect the high-pressure injector for physical damage or leaks.
- Check the wiring harness for any signs of damage or corrosion.
- Test the injector circuit for proper voltage and continuity.
- Use a diagnostic scanner to read the fault code and associated data from the ECM.
How to fix DTC P3121 on BMW
Fixing the DTC P3121 on a BMW typically involves addressing the root cause of the issue, which may include replacing the faulty high-pressure injector, repairing damaged wiring, or fixing poor electrical connections.
- Replace the Cylinder 6 high-pressure fuel injector.
- Repair any damaged wiring in the injector circuit.
- Clean or replace any corroded electrical connectors.
- Clear the fault code and perform a test drive to ensure the issue is resolved.
How to erase DTC P3121 on BMW
To erase the DTC P3121 on a BMW, you can use a diagnostic scanner to clear the fault code from the ECM’s memory. After fixing the underlying issue causing the fault code, clearing it will reset the check engine light and allow for a fresh monitoring cycle.
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.