Check engine light appeared (DTC Code P04F0) - UPDATE

[Fiesta fan]

Hi everyone,

Still relatively new to owning a Fiesta ST, only driven for about 100-140 miles (received it on November 16th, so less than a month of ownership).

Sadly, I just got a check engine light while driving on the highway.

I was driving perfectly normally, no issues on the way to some stores. Then on the way back, I decided to go about 85% full throttle (around 4k RPM on 5th gear on the highway), then a check engine light appeared.

Thankfully I was able to make it back home, without any issues, checked underneath the car and the engine bay....no major issues can be seen, other than some rattling / ticking noises which I believe is "normal" for the GTDI engines from what I've heard.

Went to autozone, 0.5 miles away from where I was and decided to get it checked since I couldn't find my old OBD2 scanner, attached is what they could find.

Doesn't look like it's a common issue for the fiesta ST after trying to search the forums. It looks like it has happened to other Ford models however. I still haven't been able to find an answer anywhere as to what it could be though.

It's a 2019 with 32.9k miles, only mod from what I can see is a whoosh intake tube. Will be going to the dealership, but for now, has anyone else run into this issue? Any help or insight is greatly appreciated as always!!

 

[Fiesta fan]

Hi everyone,

I've kind of left the fiesta on the backburner a little because of the holidays + constantly running into issues and it being at the dealership.

I thought I'd give a follow up since the original post.

I finally got the car back from the dealership ( it went to the dealership twice for issues since I was last here).

Today i finally got the chance to drive the car, but the check engine light came on for a THIRD time within the past month or so.

I got the same exact DTC code as I did last time.
As you can see from the picture, I've driven the car roughly 60 miles since I last had it.

I am DESPERATE now, as I haven't had a single day where I could enjoy this car since buying it on November.

Has anyone had this issue / DTC code before? I am desperate for answers or any lead.

So far the dealership has replaced the air intake hose, and the purge valve in the past month.

Any help or advice would be GREATLY APPRECIATED.

 

[TyphoonFiST]

Hi everyone,

I've kind of left the fiesta on the backburner a little because of the holidays + constantly running into issues and it being at the dealership.

I thought I'd give a follow up since the original post.

I finally got the car back from the dealership ( it went to the dealership twice for issues since I was last here).

Today i finally got the chance to drive the car, but the check engine light came on for a THIRD time within the past month or so.

I got the same exact DTC code as I did last time.
As you can see from the picture, I've driven the car roughly 60 miles since I last had it.

I am DESPERATE now, as I haven't had a single day where I could enjoy this car since buying it on November.

Has anyone had this issue / DTC code before? I am desperate for answers or any lead.

So far the dealership has replaced the air intake hose, and the purge valve in the past month.

Any help or advice would be GREATLY APPRECIATED.

View attachment 65088

So its still under warranty? If so id be brining it back to them to Fix it. The only other thing is the Charcoal canister solenoid*

 

[SteveS]

Read this page about that code: https://www.kbb.com/obd-ii/p04f0/
Every time the car is driven, a test of the evaporative fuel system is done, which involves pressurizing the evaporative system. The code you're getting means it isn't able to pressurize the system. There's a long list of possible causes in that article, but they all have one thing in common: they allow air pressure to leak out, keeping the system from being able to build the required pressure. The leak can be anywhere from the capless fuel cap to the intake manifold area where the evaporative system pipes and hoses and valves are, including the charcoal canister near the fuel fill/tank and its associated hoses.

This is not an easy fault to track down. The good thing is that it doesn't affect driveability. So if it takes time, don't worry. In the days before emissions inspections (or in places where there are none) people often just let this one go. We had an old 2005 Scion tc that had this code and never did anything with it. Six years ago we sold it to a friend who is still driving it with that code.

If you want to or need to track it down, the first step is a visual inspection of the entire evaporative system for cracked hoses, loose connections, and the like. Usually it's not found that easily, so along with that a smoke test needs to be done. If no leak is found that way, there is no solution left but the parts cannon. Many people start with this step. But you'd have to replace the whole evaporative harness/valve assembly in the engine compartment, the charcoal canister, and the fuel cap at least.

 

[Downsy]

A smoke checker is worth it's weight in whatever valuable commodity you deal in. I home built one using a paint can, a propane grill regulator (regulates to 1psi or there abouts), a cheap soldering iron, an old shirt as a wick, some epoxy and a bottle of baby oil. Helped me track down numerous small vacuum leaks on old Jeeps.

Legit ones used to be quite pricey. But the market is flooded with them now and they're much easier to come by. You can spend anywhere from 600 dollars to now 60-70 dollars on some no name machine.

SMOKE TESTERS ON AMAZON

 

[Fiesta fan]

Hi everyone, thanks for the replies!! I'm currently at the dealership and requested to see the car while it's being looked at by the tech.

I will also bring up the canister near the fuel tank, and the fuel cap or related parts near there as well.

But before i came in, I thought I'd take a quick look at the engine bay for anything worth bringing up.

The purge valve and new OEM air intake hose that were replaced last month because of the same check engine light, all look fine and connected, so no issues there. But I took a close look at the intake and wondered if you guys have a connector here? I am not sure what it's missing and if it's evap related or not. I only found 1 or 2 pictures online on a stock engine to show what i'm talking about.

Would anyone know what's supposed to be connected here? It's connected to the air intake.

It has a small cap on it...

Here's a closer look and after I removed the cap.


And here's the best picture I could find online, it looks like there's supposed to be something connected there.



Thank you as always