Evaporative Emission System Leak Detection Pump Control Circuit
Problem with the control circuit for the leak detection pump in the evaporative emissions system.
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What it means (plain English)
The car's computer is having trouble communicating with the pump that checks for gas leaks in the evaporative emissions system.
What the computer is actually seeing
The ECM sees a fault in the control circuit for the leak detection pump; typically it detects an out-of-range voltage signal (below 0.5 volts or above 4.5 volts) when it should be receiving a proper signal.
What a healthy reading looks like
When the pump is commanded on, the ECU expects 0.5-4.5 volts at the pump control circuit; if not, a fault code will be triggered.
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. Inspect the wiring and connectors for the leak detection pump for damage or corrosion. IF damaged, repair as necessary. DECISION: If solid, proceed to step 2.
- 22. Measure the voltage at the pump connector with the key on and engine off. EXPECT 0.5-4.5 volts. IF voltage is within spec, suspect the pump; if not, troubleshoot wiring back to the ECU. DECISION: If the voltage is correct, proceed to step 3; if not, repair wiring as necessary.
- 33. Check the resistance of the leak detection pump. EXPECT 20-40 ohms. IF resistance is out of spec, replace the pump. DECISION: If resistance is proper, suspect a bad ECU.
Common causes
- Open or shorted wiring in the pump circuit
- Faulty evaporative emission leak detection pump
- Bad ECU and/or connectors
- Electrical connections corroded or loose
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code present?
Yes, but you should fix it soon to prevent emissions issues and pass inspections.
Will this code come back after I clear it?
It may come back if the underlying issue isn’t fixed.
Why does this code come with others like P2400?
These codes are often related to the same system and indicate similar or cascading faults.
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