BMW DTC P0402 – EGR ‘A’ Flow Excessive Detected
DTC P0402 meaning on BMW
The Diagnostic Trouble Code (DTC) P0402 for BMW indicates that the Engine Control Module (ECM) has detected excessive flow in the Exhaust Gas Recirculation (EGR) system. The EGR system is responsible for recirculating a portion of the engine’s exhaust gases back into the intake manifold to reduce combustion temperatures and emissions.
BMW DTC P0402 symptoms
Symptoms of a DTC P0402 on a BMW may include:
- Check Engine Light (CEL) illuminated on the dashboard
- Decreased fuel efficiency
- Engine hesitation or misfiring
- Increased emissions
BMW DTC P0402 causes
Common causes of a DTC P0402 on a BMW include:
- Clogged or restricted EGR valve
- Faulty EGR temperature sensor
- Carbon buildup in the EGR system
- Wiring or connector issues in the EGR system
BMW DTC P0402 seriousness
While a DTC P0402 may not cause immediate drivability issues, it can lead to increased emissions and reduced fuel efficiency over time. Ignoring this code can also potentially cause damage to other engine components.
How to diagnose DTC P0402 on BMW
To diagnose a DTC P0402 on a BMW, you can perform the following steps:
- Use a diagnostic scanner to retrieve the fault code and freeze frame data
- Inspect the EGR valve and associated components for any signs of damage or blockages
- Check the EGR temperature sensor for proper operation
- Inspect the wiring and connectors in the EGR system for any issues
How to fix DTC P0402 on BMW
To fix a DTC P0402 on a BMW, you can try the following solutions:
- Clean or replace the EGR valve if it is clogged or faulty
- Replace the EGR temperature sensor if it is malfunctioning
- Clean out any carbon buildup in the EGR system
- Repair any wiring or connector issues in the EGR system
How to erase DTC P0402 on BMW
To erase a DTC P0402 on a BMW, you can use a diagnostic scanner to clear the code after the underlying issue has been addressed. Once the fault has been fixed, the ECM can be reset to clear the code and turn off the Check Engine Light.
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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