Is it the O2 Sensors or something else? 2009 Chrysler Town and Country

Check engine light started turning on, intermittently, a few weeks ago in my 2009 Chrysler Town and Country

Intermittently means it turns on for a day then shuts off again for a few days. Then comes back on again and stays on for anywhere from a full day to several days in a row - rinse repeat this kind of behavior.

The light does not flash.

The car shudders lightly to moderately in idle and while driving.

Local car shop tested for this and found code PO455 and said I should start by changing out the fuel cap. I didn’t know the right questions to ask them more about it at the time, but I felt it was more than just that since the light doesn’t stay on, consistently.

Is this code for the emissions system related to the O2 sensors needing to be replaced or more likely something else, like the fuel injectors? Or perhaps something even worse?

That code means that your evaporative emissions system is not holding vacuum when it self tests.

The system includes gas cap. fuel filler neck, gas tank, purge valve and vapor canister and all hoses and fittings and clamps between.

Air is getting in someplace.

Damaged or loose gas cap is the most common reason for that code.

On a 10 year old van, replacing the gas cap is an obvious, cheapest and easiest thing you can do that might just make this go away. It is worth a try.

The gas cap had no obvious signs of damage that I could determine.

I bought a new gas cap but replacing the old one with it, didn’t fix the issue. Light is still on.

Perhaps it’s a hose or something else.

Evaporative emission system leaks aren’t always caused by loose or failing fuel caps, a close inspection of the evap system is needed to identify the leak.

1 Like is my go-to place for Chrysler-specific problems. There are several discussion groups there, all about Chrysler Corp. vehicles past, present, and future.

If you are losing some coolant and have a shuddering problem, look for a coolant leak at the intake manifold gasket, on the side near the coil pack, or on the opposite side.

On my 2003 T & C minivan I had an evaporative leak I could not find for years. Took it to my mechanic because I was selling it to my granddaughter.

Turned out to be a crack in the metal plate where the gas lines go into the plastic fuel tank. The weight of the pump hanging from that plate finally cracked it.

The shuddering is probably a separate problem. Unless the shuddering started at the same time the check engine light started coming on, I’d consider those as two separate independent problems. As mentioned above the code is saying something in the evap system is leaking. Taking the car in for a shop inspection is how to find where the leak is occurring. As an analogy, say you have a swimming pool, and you know you have to fill it up every day with 100 gallons of water to keep it full. When before you never had to add more than 10 gallons a day. You know something in the pool or the plumbing is leaking, but you have no idea where. Shops have methods to determine where the leak is occurring. One of those, they have a machine that blows a safe form of visible smoke into the evap system. Then they just watch for where the smoke comes out.

Another symptom occurring occasionally, is the car shutting off after turning the key and starting up the car; you have to re-turn the key, usually only once more, to get the engine to start and keep running.

At the shop, mechanic cleared codes so engine light shut off.

He said it’s likely the purge solenoid that’s the problem - a strong likelihood, though not necessarily the reason as to why the car sometimes has some starting trouble.

If that’s the case - hoping to get to the bottom of this, soon - it doesn’t sound very costly a repair…

A faulty purge solenoid could cause hard-starting. That’s an electrically actuated valve which allows gasoline stored in the canister to move into the engine. It’s only supposed to open when the engine is already running, and usually not until the rpm and/or vehicle speed is above a certain limit. The purge valve should be completely closed during cranking. If it fails “open” it could cause the engine to flood during cranking and make the engine difficult to start. There might be a flexible hose from the purge valve to the throttle body the shop could temporarily clamp off to prove this theory, before replacing the valve.