BMW DTC P1402 – Cold Start EGR ‘B’ Control Stuck Open
DTC P1402 meaning on BMW
The Diagnostic Trouble Code (DTC) P1402 for BMW indicates an issue with the Cold Start Exhaust Gas Recirculation (EGR) ‘B’ Control being stuck open. The EGR system is responsible for recirculating a portion of the exhaust gases back into the engine cylinders to reduce emissions and control combustion temperatures. When the EGR ‘B’ control is stuck open during cold start conditions, it can lead to improper engine performance and increased emissions.
BMW DTC P1402 symptoms
Symptoms of the DTC P1402 on a BMW may include rough idling, decreased fuel efficiency, engine hesitation, and potentially an illuminated Check Engine Light on the dashboard. Additionally, the vehicle may fail emissions tests due to increased emissions output.
BMW DTC P1402 causes
The most common causes of the DTC P1402 on a BMW include a faulty EGR valve, carbon buildup in the EGR system, electrical issues with the EGR control circuit, or a malfunctioning EGR temperature sensor. These issues can prevent the EGR ‘B’ control from operating properly, leading to it being stuck open.
BMW DTC P1402 seriousness
While the DTC P1402 may not cause immediate drivability issues, it is important to address this problem promptly to prevent further damage to the engine and ensure compliance with emissions regulations. Ignoring the issue can lead to decreased fuel efficiency, increased emissions, and potential long-term engine damage.
How to diagnose DTC P1402 on BMW
To diagnose the DTC P1402 on a BMW, a mechanic would typically use a diagnostic scanner to retrieve the fault codes stored in the vehicle’s computer system. They would then perform a visual inspection of the EGR system components, check the EGR valve operation, test the EGR temperature sensor, and inspect the wiring and connectors for any signs of damage or corrosion.
How to fix DTC P1402 on BMW
To fix the DTC P1402 on a BMW, the following steps may be taken:
- Inspect and clean the EGR valve to ensure proper operation.
- Check for carbon buildup in the EGR system and clean if necessary.
- Test the EGR temperature sensor and replace if faulty.
- Inspect the EGR control circuit for any electrical issues and repair as needed.
- Reset the fault codes and perform a test drive to ensure the issue has been resolved.
How to erase DTC P1402 on BMW
To erase the DTC P1402 on a BMW, a diagnostic scanner can be used to clear the fault codes stored in the vehicle’s computer system. After addressing the underlying issue causing the fault code, the scanner can be used to reset the codes and clear the Check Engine Light. It is important to ensure that the root cause of the problem has been fixed before clearing the fault codes.
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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