P0406 – BMW DTC

BMW DTC P0406 – EGR Sensor ‘A’ Circuit High

DTC P0406 meaning on BMW

DTC P0406 for BMW refers to an issue with the Exhaust Gas Recirculation (EGR) Sensor ‘A’ Circuit registering a high voltage. The EGR system is responsible for recirculating a portion of the exhaust gases back into the engine cylinders to reduce combustion temperatures and emissions. The EGR sensor ‘A’ monitors the position and function of the EGR valve.

BMW DTC P0406 symptoms

Symptoms of a DTC P0406 on a BMW may include:

• Illuminated Check Engine Light
• Decreased fuel efficiency
• Engine hesitation or misfiring
• Increased emissions

BMW DTC P0406 causes

Common causes of DTC P0406 on a BMW include:

• Failed EGR sensor ‘A’
• Wiring or connector issues in the EGR sensor circuit
• Carbon buildup in the EGR system
• Faulty EGR valve

BMW DTC P0406 seriousness

While a DTC P0406 may not cause immediate drivability issues, it can lead to increased emissions and reduced fuel efficiency. Ignoring this fault can potentially cause long-term damage to the engine and emission control systems.

How to diagnose DTC P0406 on BMW

To diagnose a DTC P0406 on a BMW, a mechanic may perform the following steps:

1. Use a diagnostic scanner to retrieve the fault code and freeze frame data
2. Inspect the EGR sensor ‘A’ and its wiring for any visible damage
3. Test the EGR sensor’s voltage and resistance
4. Check for carbon buildup in the EGR system

How to fix DTC P0406 on BMW

To fix a DTC P0406 on a BMW, you may need to:

1. Replace the EGR sensor ‘A’ if faulty
2. Repair any damaged wiring or connectors in the EGR sensor circuit
3. Clean out any carbon deposits in the EGR system
4. Replace the EGR valve if necessary

How to erase DTC P0406 on BMW

To erase a DTC P0406 on a BMW, you can:

1. Use a diagnostic scanner to clear the fault code
2. After fixing the underlying issue, drive the vehicle to allow the system to perform a self-check and verify the repair

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.