P04AC
EVAP System Purge Control Valve B Circuit Low
Same as P04AB with the control line shorted to ground. The evaporative system captures fuel vapor from the tank and purges it into intake; leaks or stuck purge valves leak hydrocarbons and cause emissions failures.
Same as P04AB with the control line shorted to ground. The evaporative system captures fuel vapor from the tank and purges it into intake; leaks or stuck purge valves leak hydrocarbons and cause emissions failures.
Common causes
- high
Control line shorted to ground
One of the most commonly reported causes for this code — check this first.
Typical part cost: $90-310
- low
Connector pins corroded - high contact resistance
Less common, but worth ruling out after the more likely causes.
Typical part cost: $90-310
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for P04AC.
Unlock causesFree forever · No credit card
First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
Get the full step-by-step diagnosis
Create a free Wrenchify account to unlock the rest for P04AC.
Unlock diagnosisFree forever · No credit card
Related codes
See related trouble codes
Create a free Wrenchify account to unlock the rest for P04AC.
Unlock related codesFree forever · No credit card
Frequently asked questions
What does P04AC mean?
P04AC means "EVAP System Purge Control Valve B Circuit Low". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P04AC?
control line shorted to ground; connector pins corroded - high contact resistance; harness chafing through insulation — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
Get the full P04AC diagnosis for your vehicle
Year, make, model + step-by-step repair help — free plan included.