Code P219a- really the 02 sensor, or something else?

[mdirks]

Hey everyone, I realize I'm not the first person with the code P219a and have investigated it a little bit. (I just went to autozone and used their OBD scanner since I don't have a fancy COBB accessport yet.) I was somewhat surprised that it specifically suggested the downstream "bank 1 O2 sensor" given the variety problems Fiesta STs can get in association with this code.


My car had been doing the "chugg" at idle right after filling up (but only on a full/overfull tank.) for sometime but no warning light. Even passed emissions fine last weekend.

Mods: Oil Catch can, K&N filter (both from previous owner).

About a month ago, I was rear-ended but as far as I can tell, only the bumper needs replaced. (No mechanical damage as far as I can tell.) So tomorrow I'll be handing the keys over to a body shop and driving a rental.

I'm curious if you guys think it really is the O2 sensor (e.g. I should order one while the bumper is being replaced, or wait to diagnose it myself later)?

 

[M-Sport fan]

Model YEAR/miles?

 

[mdirks]

'17, about 47K miles.

 

[SteveS]

Although that code CAN come from the O2 sensor, there are a lot of other possible causes. This page goes over those possibilities and at the end has a suggested diagnostic scheme, rather than just replacing parts. It can be as simple as a vacuum leak (though finding those isn't necessarily simple). And although the code for problems with the evaporative emissions system is P0403, one of the causes for that one (which goes with the overfueling stumble), is also a vacuum leak.

https://partsavatar.ca/p219a-obd-ii...-imbalance-solution-oxygen-sensor-fuel-filter

 

[mdirks]

Thanks for the tips. I will look into it.( For now the car is off at the body shop, so I'm rediscovering why CVT's are terrible.)

 

[mdirks]

Update- have received car back from body shop. They presumably disconnected the battery so the warning light has disappeared. In the interim I'm throwing on my first upgrade- a COBB intake. Cleaned the MAF while I was along the way.

 

[mdirks]

Hopefully a final update- driven the car a few hundred miles and so far no warning light (fingers crossed).