P144C is a Ford-only DTC trouble code, and as such, it applies to your Mercury Grand Marquis. It indicates that the EVAP canister purge check valve is not performing within spec.
P144C is most often fixed by replacing the EVAP purge valve assembly (due to the purge valve being stuck open or closed), which can be a little tricky depending on how tight your Grand Marquis’s engine compartment is.
The EVAP purge check valve is part of the Evaporative Emissions System, which exists to control fuel vapor. Therefore, P144C should not be considered a breakdown risk when it is the only code stored in your Grand Marquis’s PCM.
P144C Definition: EVAP Purge Check Valve – Performance
Here’s what happened for you to get P144C in your Grand Marquis:
The EVAP purge valve pulls fuel vapor from the gas tank and sends it into the intake manifold. From there, it burns off cleanly.
Your Mercury’s PCM performs a test on the EVAP check valve during light boost conditions, one time per drive cycle.
It is checking to see if the fuel tank pressure exceeds the calibrated amount or if the fuel tank vacuum is less than the calibrated amount for a certain amount of time. If it doesn’t see the proper values, P144C is triggered.
P144C Symptoms: Mercury Grand Marquis
The only symptom you should expect to see with P144C is the check engine light. A failure in the EVAP system should not affect the way your Grand Marquis runs and drives.
Mercury Grand Marquis: P144C Causes
P144C is an increasingly common code on turbo-charged vehicles. Here are the most common causes of P144C in the Grand Marquis:
- Bad EVAP check valve
- Bad EVAP Ejector
- EVAP check valve stuck open or closed
- Blocked EVAP connection at the intake air system
Check out the video below. If P144C is intermittent, it can be challenging to chase down. You can start by inspecting the EVAP hoses. After that, you can use a scanner to command the purge valve to open and close. Verify that it does.
Conclusion
A bad EVAP check valve often causes P144C in the Mercury Grand Marquis. Good luck fixing chasing down the problem!