Evaporative Emission Control System Vent Control Circuit
The vent control circuit for the evaporative emission system is malfunctioning.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
This code means the vehicle is having trouble managing the fuel vapor emissions, possibly due to a bad vent valve or electrical issue.
What the computer is actually seeing
The powertrain control module (PCM) checks for input from the EVAP vent control circuit. It expects a normal voltage signal (typically 0.5-4.0 volts) indicating the valve is functioning. If it sees an open circuit (typically >4.5 volts) or a short (Voltage <0.5 volts), it triggers this code.
What a healthy reading looks like
Voltage on the vent control circuit should be between 0.5 and 4.0 volts with the ignition on and engine off.
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 to the EVAP vent valve for damage or corrosion. If there are issues, repair them. Decision: If wiring is good, proceed to step 2. If damaged, fix and retest.
- 22. Check the EVAP vent valve operation by applying direct power (12V) to the valve. It should click and open. Decision: If it operates, proceed to step 3. If it doesn't, replace the vent valve.
- 33. Measure the voltage at the EVAP vent valve connector with the ignition on (engine off). Expect 0.5-4.0 volts. Decision: If within range, suspect PCM. If not, trace wiring back to the PCM.
Common causes
- Faulty EVAP vent valve
- Damaged wiring or connectors in the vent circuit
- Faulty PCM (less common)
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but expect a slight increase in emissions and possibly a check engine light pending repairs.
Will this code come back after clearing?
It can come back if the underlying issue is not fixed, like a faulty vent valve or damaged wiring.
Why does this relate to other EVAP codes?
They all involve the evaporative emission system, and issues in one area can trigger multiple codes.
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