Evaporative Emission System Leak Detection Pump Switch/Signal Low
The leak detection pump switch or signal is low, indicating a problem with the evaporative emissions system.
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What it means (plain English)
The car's computer is noticing that it can't detect a leak in the fuel vapor system, likely due to a faulty switch or pump that should signal if there's a problem.
What the computer is actually seeing
The engine control module (ECM) expects to see a certain switch status (high/low) from the leak detection pump. When the pump is activated, the switch should signal a status change; if it doesn't, the code triggers.
What a healthy reading looks like
The expected voltage at the leak detection pump switch should range between 0.5V to 5V when the pump is operational. If the switch is open, it should be around 0V.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Visually inspect the wiring and connectors to the leak detection pump for damage or corrosion. If found, repair or replace.
- 22. Check the fuel tank pressure sensor. Ensure it's functioning correctly; if faulty, replace it.
- 33. Use a scan tool to command the leak detection pump to run and monitor switch status. If the pump doesn't activate, replace the pump.
- 44. If the pump operates but there's still a low signal, check wiring continuity from the pump to the ECM. Repair any issues found.
Common causes
- Faulty leak detection pump
- Damaged wiring or connector to the pump
- Failed fuel tank pressure sensor
- Plugged lines or filters in the vapor system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, it's safe to drive but fix it soon to prevent potential emissions system problems.
Will this code come back after clearing?
It might come back if the underlying issue isn't fixed; monitor for reoccurrence after repairs.
Why does this code pair with P0455?
P0455 indicates a large leak, which could relate to issues with the same components involved in this code.
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