P1477 – BMW DTC

BMW DTC P1477 – Leakage Diagnostic Pump Reed Switch Did Not Open

DTC P1477 meaning on BMW

DTC P1477 on a BMW indicates a fault with the Leakage Diagnostic Pump Reed Switch not opening. The reed switch is a component within the evaporative emissions system that is responsible for detecting leaks in the fuel vapor system. When the switch fails to open as expected, it triggers the P1477 diagnostic trouble code.

BMW DTC P1477 symptoms

Symptoms of DTC P1477 on a BMW may include:

• Check Engine Light illuminated on the dashboard
• Decreased fuel efficiency
• Increased emissions
• Issues passing emissions tests

BMW DTC P1477 causes

The common causes of DTC P1477 on a BMW include:

• Defective Leakage Diagnostic Pump Reed Switch
• Wiring or connection issues in the evaporative emissions system
• Faulty evaporative emissions system components

BMW DTC P1477 seriousness

While DTC P1477 may not cause immediate drivability issues, it is important to address this fault promptly. Ignoring the problem can lead to increased emissions, reduced fuel efficiency, and potential issues passing emissions tests.

How to diagnose DTC P1477 on BMW

To diagnose DTC P1477 on a BMW, a mechanic may perform the following steps:

1. Use a diagnostic scanner to retrieve the fault code
2. Inspect the Leakage Diagnostic Pump Reed Switch for proper operation
3. Check the wiring and connections in the evaporative emissions system
4. Perform a smoke test to detect any leaks in the fuel vapor system

How to fix DTC P1477 on BMW

To fix DTC P1477 on a BMW, the following steps may be taken:

1. Replace the faulty Leakage Diagnostic Pump Reed Switch
2. Repair any damaged wiring or connections in the evaporative emissions system
3. Address any other identified issues with the evaporative emissions components

How to erase DTC P1477 on BMW

After the underlying issue causing DTC P1477 on a BMW has been resolved, the fault code can be cleared using a diagnostic scanner. This will erase the code from the vehicle’s memory 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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