P219A Code, no check engine light

[peglegdev]

So the P219A code came up from a random engine code check due to mpg loss, I don’t have a check engine light, but recently I’ve lost about 6mpg having to fill up at 250-260 miles, same fuel 93 octane same gas station, I’ve read a couple of forums saying it could be a couple of things but none of them state fuel mpg loss I don’t wanna start replacing parts I don’t need to. If anyone could point me in a direction or if someone who has ran into this issue help me out, please and thank you.

 

[SteveS]

As you've no doubt already found, the list of things that can cause this is large.

• Engine vacuum leak
• Defective oxygen sensor
• Engine exhaust leaks
• Faulty mass air flow or manifold air pressure sensor
• Faulty Exhaust Gas Recirculation (EGR) system
• Positive Crankcase Ventilation (PCV) system leaks
• Bad fuel pump
• Leaking fuel injectors
• Low fuel pressure
• Clogged fuel filter
• Issues with the electrical wiring and connectors

What I have found on the Focus ST forum is a lot of posts where the fix was replacing the upstream O2 sensor. Sometimes that ended up only a temporary reprieve and they had to go down the list of all the other things.

 

[DEss]

So the P219A code came up from a random engine code check due to mpg loss, I don’t have a check engine light, but recently I’ve lost about 6mpg having to fill up at 250-260 miles, same fuel 93 octane same gas station, I’ve read a couple of forums saying it could be a couple of things but none of them state fuel mpg loss I don’t wanna start replacing parts I don’t need to. If anyone could point me in a direction or if someone who has ran into this issue help me out, please and thank you.

Did you find out what the cause was?

DS