2003 Taurus Mass Air Flow (MAF) - need help

another car issue was discussed in another thread, but there’s been more developments that i’m now concerned about, & don’t know how these fit into the overall picture.


[as a reminder, i had this minor work done very recently: oil change, tire rotation, air filter, & windshield wiper change within last couple weeks - i am always suspicious after i have a garage do anything, especially if something else goes wrong the next day, or week.]

this taurus (ses) has about 47,000 miles on it.

i haven’t gotten to look into having the a/c hose blown out (or whatever needs to be done), & my engine light went on the same day i had been getting responses to the passenger floor water issue.

i went to auto zone, & this is the (confusing) reading i got. (i would have thought it would be related to my water problem, but looks like something else completely? isn’t the timing rather strange tho?)





Fuel trim bank one condition


The powertrain control module uses the oxygen sensor to calculate the Air/Fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

Probable cause

1. - If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) sensor

2. - Oxygen sensor defective

3. - Ignition misfire-repair

4. - Fuel injector problem



The ECM has detected a rich or lean Air/Fuel ratio condition on engine bank two.

Probable cause

1. - If bank one and two are set together suspect fuel pressure or MAF sensor fault

2. - Failed HO2521 (Heated oxygen sensor - Bank 2 Sensor 1)

3. - Ignition misfire condition

4. - Fuel injector problem

5. - Engine mechanical condition


the guy at auto zone said the mass air flow sensor part is $130, & said it’s easy to replace (well, not for me!)… but suggested using fuel system cleaner (& possibly air flow sensor spray) first before doing that other repair.

i am very confused… why is all this happening right after i took my car in for minor work? could any of it be related to that?

also… this isn’t in any way related to my wet floor, correct?

i’m baffled, & calling on you guys as usual.

p.s. i’m sorry if this is a bit of a repeat, but i can’t figure out how to delete the other post.

DTC P0171=System Too Lean (bank one).
DTC P0174=System Too Lean (bank two).

Because the air filter was serviced recently, check to see if any hoses or connections between the air filter box to the throttle body are loose or disconnected. If there’s any air leaking into the engine after the MAF sensor it will set both these codes.


i will try to check that… i did look at some photos that showed where the unit is, & seem to have noticed it under the hood, but not exactly sure which things to look at as far as solid connections.

i did have someone disconnect the battery for a minute, & now the engine light hasn’t come back on. i figured that it would return after awhile (if not immediately) if there were a true problem, or it was just related to me just fueling up before the light came on. (& i don’t remember overfueling)