BMW DTC P1421 – Secondary Air System (Bank 2)
DTC P1421 meaning on BMW
The DTC P1421 on a BMW indicates a fault in the Secondary Air System for Bank 2. This system is responsible for reducing emissions during cold starts by injecting fresh air into the exhaust system to help with the combustion process.
BMW DTC P1421 symptoms
Symptoms of a DTC P1421 on a BMW may include:
- Check Engine Light illuminated
- Rough idle during cold starts
- Decreased engine performance
- In some cases, there may be no noticeable symptoms
BMW DTC P1421 causes
Common causes of a DTC P1421 on a BMW include:
- Faulty Secondary Air Injection Pump
- Blocked or leaking air lines
- Malfunctioning Secondary Air Injection Valve
- Electrical issues in the system
BMW DTC P1421 seriousness
While a DTC P1421 may not always cause immediate drivability issues, it is important to address the problem promptly to ensure optimal engine performance and emissions compliance. Ignoring the issue can lead to increased emissions and potential damage to other components.
How to diagnose DTC P1421 on BMW
To diagnose a DTC P1421 on a BMW, a mechanic may perform the following steps:
- Use a diagnostic scanner to retrieve the fault code
- Inspect the Secondary Air Injection Pump and associated components for damage or leaks
- Check the electrical connections and wiring for any issues
- Perform a smoke test to identify any air leaks in the system
How to fix DTC P1421 on BMW
To fix a DTC P1421 on a BMW, the following steps may be taken:
- Replace the faulty Secondary Air Injection Pump
- Repair or replace any damaged air lines or components
- Clean or replace the Secondary Air Injection Valve if necessary
- Ensure all electrical connections are secure and functioning properly
How to erase DTC P1421 on BMW
After the issue causing the DTC P1421 on a BMW has been addressed, the fault code can be cleared using a diagnostic scanner. This will reset the Check Engine Light and allow the vehicle’s onboard computer to monitor the system for any new faults.
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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