Car Stalls After PCV Valve Replacement

2012 Hyundai Sonata GLS.

I replaced my valve cover gasket and snapped the tip off the pcv valve when putting it back on. I started the car to inspect for any leaks and everything seemed fine.

I took my other car to grab a new pcv valve. Replaced it and hooked up the tube. Now, the car will start, but dies immediately after. Bought another valve, same issue.

If the vacuum hose is disconnected from the pcv valve, the car will start and run. If i put my finger over the ending of the vacuum line it dies. If i attach it to the pcv valve, it dies. Only starts and continues to run if not attached to valve.

I wonder if the new PCV valve is somehow bad or defective?

It sounds like the motor is relying on the air coming through the PCV hose to run. Is the throttle plate sticking closed?

hmmm, very puzzling … It seems like it has to either be the pcv valve itself, or something to do with the valve cover removal and reinstall. The pcv valve is designed to allow only a little air flow into the engine at idle, but more flow at higher engine rpms. I’m guessing your new pcv valve the problem, not allowing any air flow at all, and is defective. Or it is installed in the wrong orientation. In my vehicles it can only be installed one way, but that might not be the case with your Sonata, don’t know.

Another idea, in the process of removing the valve cover to replace the gasket, maybe upon reinstalling the valve cover you’ve got the pcv hoses mixed up.

I believe I fixed it. Why this worked or whether it’s a coincidence… no clue.

I woke up this morning and started the car, it immediately died. I unattached the hose on the pcv valve like previously, it started right up and ran.

So with the car off, I attached the hose to the pcv valve again. Then i disconnected the negative battery terminal. I did some things around the house for maybe an hour or so. Went back outside and reconnected the battery terminal. It started up and ran with everything connected like it should. Drove around with no issues.

Try cleaning the electronic throttle body.


disconnecting battery may have caused the drivetrain computer to forget the engine’s learned idle parameters. It then has to substitute a set of idle parameters that are guaranteed to run the engine for enough time to re-learn the proper values. The idle parameters are l related to the amount of airflow through the pcv valve at idle, which may have changed w/new pcv valve.