Diagnostic Trouble Codes P0172 P0175

I thought this was worth mentioning since I wasn’t able to find anything about it on the internet when I was researching it. Also, it should apply to XKs as well as our XFs.

Recently, my check engine light came on. I didn’t notice any symptoms of the car running differently, but the light stayed on even after restarts and cooling down. Using my scan tool, I found that my car had DTCs P0172 and P0175 which are both codes indicating “System too rich” (one is for Bank 1 and the other code is for Bank 2).

After checking quite a few things on the car involving the mass air flow sensor, TPS, oxygen sensors, and MAP, I decided to try removing both MAF sensors and cleaning them. Surprisingly, this did the trick and the DTCs haven’t come back since. I’m bringing this up because normally a dirty MAF will cause the opposite and result in a lean condition, but apparently not on our cars.

I know cleaning them will only be a short term solution, so I’ll be purchasing some new ones soon. Hopefully, this will be the last issue for a while. Its been exactly one year since I got my car, and thus far it hasn’t exactly been reliable. It hasn’t left me stranded or broke down, but I’ve dealt with several error messages that have popped up on the dash. Fingers crossed that my car just wanted some attention because it felt neglected by the previous owner and now realizes it has a sugardaddy for an owner.

On two of my vehicles, neither Of them Jags, those codes will also be created by very dirty air filters. I live on a dirt road and much dust is thrown up by passing vehilces

That’s interesting Larry. Because the air filters are located before the MAF sensors, I would expect the MAF sensors to sense the lack of airflow and reduce the fuel trims appropriately. Therefore, I’d expect the computer to compensate until the adjustment crosses a threshold, which would then trip the DTC codes. How dirty were those air filters? Based off what I just said, I would think they had to be filthy to trip a code.

I believe that’s exactly what happens. The filters were really dirty. Again I live on a well traveled dirt road. And the F150 has a K&N on it so that oil latches on to the dust. Replacing/cleaning the filters for me solved the issue. TheFord actually triggered when accelerating pretty hard. It would never trigger if it was idling. So at low need for air the MAF could adjust. I’m also at 9000’ elevation. I’m already 25% shy on air. Dirty air filter probably takes the computer out of range of what the parameters are

I think that confirms it. If it only got triggered when accelerating hard, it definitely went past the point it could adjust for.

I run K&Ns in almost everything, but fortunately I don’t live on a dirt road. On the flip side though, that gives you an excuse to tinker on your cars more, so not all bad.

I put the K&N on as it’s cheaper than changing paper filters as often as I need to change. I probably seed to get another one so I can swap out after cleaning as it takes a day to dry.

I reeeelaly don’t need more things to tinker with😁