BMW DTC P1390 – Ionic Current Voltage Selection Measuring-Circuit Low
DTC P1390 meaning on BMW
The Diagnostic Trouble Code (DTC) P1390 for BMW refers to the Ionic Current Voltage Selection Measuring-Circuit Low. This code indicates that there is a low voltage signal detected in the circuit responsible for measuring the ionic current in the engine.
BMW DTC P1390 symptoms
Symptoms associated with BMW DTC P1390 may include:
- Check Engine Light (MIL) illuminated on the dashboard
- Engine running rough or misfiring
- Reduced engine performance
- Potential stalling or difficulty starting the engine
BMW DTC P1390 causes
Common causes of BMW DTC P1390 include:
- Faulty ionic current sensor
- Wiring or connection issues in the measuring circuit
- Corrosion or poor contact in the sensor or circuit
- ECU (Engine Control Unit) malfunction
BMW DTC P1390 seriousness
While BMW DTC P1390 may not always result in immediate drivability issues, it is important to address this code promptly to prevent potential engine damage or further complications. Ignoring this code can lead to poor engine performance and increased emissions.
How to diagnose DTC P1390 on BMW
To diagnose BMW DTC P1390, a mechanic would typically perform the following steps:
- Use a diagnostic scanner to retrieve the fault codes and freeze frame data
- Inspect the ionic current sensor and its wiring for any visible damage or corrosion
- Check the connections and terminals in the measuring circuit for proper contact
- Perform a voltage test on the sensor and circuit to determine if the signal is within specifications
How to fix DTC P1390 on BMW
Depending on the root cause of BMW DTC P1390, the following steps may be taken to fix the issue:
- Replace the faulty ionic current sensor if it is determined to be the cause
- Repair or replace any damaged wiring or connections in the measuring circuit
- Clean any corrosion or debris in the sensor or circuit contacts
- If the ECU is suspected to be faulty, it may need to be reprogrammed or replaced
How to erase DTC P1390 on BMW
To erase BMW DTC P1390, the fault code can be cleared using a diagnostic scanner. After addressing the underlying issue that triggered the code, the scanner can be used to reset the code and clear the Check Engine Light. 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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