Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with a part of the car that checks for leaks in the fuel system. It's like a little switch that didn't do what it was supposed to do.
The leakage diagnostic pump is part of the evaporative emission control system (EVAP) that checks for leaks. The reed switch is supposed to open when the pump operates, and if it doesn't, this code is triggered.
The P1477 code indicates that the reed switch in the leakage diagnostic pump failed to open as expected. This switch is crucial for monitoring the integrity of the EVAP system by ensuring that the pump can create the necessary pressure to test for leaks.
• Check Engine Light is on
• Possible fuel smell
• Failed emissions test
• Faulty reed switch
• Malfunctioning leakage diagnostic pump
• Wiring issues or poor electrical connections
EVAP: Evaporative Emission Control System
Reed Switch: A switch that opens or closes in response to a magnetic field
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connections to the leakage diagnostic pump.
• Test the reed switch for proper operation.
• Replace the faulty reed switch.
• Repair or replace the leakage diagnostic pump.
• Fix any wiring or connection issues.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $300
Moderate
• BMW 3 Series
• BMW 5 Series
• BMW X5
• Regularly inspect the EVAP system.
• Ensure proper maintenance of fuel system components.
• Address Check Engine Light issues promptly.
Sensor Issue
• Do not ignore the Check Engine Light.
• Get the vehicle inspected by a professional if you're unsure.
• Regular maintenance can prevent such issues.
Check with your vehicle manufacturer as EVAP system components may be covered under emissions warranty.
This code has been associated with vehicles that have aging EVAP systems, particularly in models with known reed switch issues.
Moderate – It won't cause immediate damage, but it should be addressed to pass emissions tests and avoid fuel vapor leaks.
Ignoring emissions-related issues can lead to failed inspections and potential fines.
• Vehicle at operating temperature
• EVAP system test cycle initiated
The leakage diagnostic pump is usually located near the fuel tank or within the EVAP canister assembly.
Q: Can I drive with a P1477 code?
A: Yes, but it's best to fix it soon to avoid emissions issues.
Q: Will a P1477 code affect my fuel economy?
A: Not directly, but unresolved EVAP issues can lead to other problems.
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Universal · Digital multimeter
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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Fitment Required · Vehicle-fitment part
Relevant when EVAP diagnosis points toward purge-flow or purge-control faults.
EVAP diagnosis often includes purge-flow and valve-control faults.
Confirm the failed valve and exact fitment before buying parts.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.