rfmlin

My 99 Windstar (3.8L engine) check engine light went on. The fault codes are P0171: System Too Lean (Bank 1) and P0174: System Too Lean (Bank 2). In some of the other forum discussions I've seen similar references where people have identified the oxygen sensor to be the culprit. Does Bank 1 and Bank 2 refer to the front and rear oxygen sensors or something else? Any other suggestions on what might be wrong?

LunaticSVT

Actually getting an error code P0171 and P0174 means that the air/fuel mixture is too lean. Most likely due to one or more of the following....

Dirty air filter, loose oil dipstick, dirty/defective MAF, dirty injectors, vacuum leak around the intake manifold, a loose vacuum hose, evaporated emmissions purge control valve could have a wire connector disconnected, or possibly bad O2's.

The Bank System refers to the following.

Bank one will line up with the number one cylinder and bank two will line up with the number 2 cylinder of your engine. From there you will have Sensor 1 which is the sensor prior to the Cat and Sensor 2 which is behind the cat.

Hope that helps.

rfmlin

Thanks LunaticSVT That helps a lot. I'll go through each one of those items you listed. Does the code reset itself after ever engine start or do I have to do something to reset it? In other words, once the problem is resolved, will the check engine light just go off?

LunaticSVT

no you will have to reset it. If I recall on the Windstars you can reset the computer by disconnecting the battery for 30 min. and then connect again.

This should clear the CEL.

warriorspoon7

I have the same problem as above. However, I changed the C2's,the fuel injectors blown out, changed the MAF, had it checked for seal problems and for leaks, still the light remained even after I had the battery disconnected. Now what?

sparkyele69

the bank 1 sensor is under the front manifold.the bank 2sensor is in the cat.converter change both of these and that should solve your problem..

sparkyele69

i disconnect the positive battery cable to clean it.and went to get this vehicle inspected an the inspector said that the moduals wernt responding an i had to drive the car awhile before it will reset itself.so i did that for a week and half 350+ miles and went back to him to inspect.and he said that they are still not responding.so i checked for a blown fuse under the console and under the hood and nothing. anybody got any suggestion???????? drive with no inspection....

rjayme7252007

Actually,i tried that and it didn't work.I went to autozone and bought an OBD2 diagnostic computer and shut the light off from there.