Smrtass498

Hello everyone - new user!

I have a 1996 F150, I6 4.9L, 2wd.

For the past....couple of years....my check engine light has been on and no matter what I do, it has stayed on. It may clear for a few hours, or a day, but always comes back. The code is P0174 or P0171 lean bank 1 or 2. I have replaced the following: All 3 O2 sensors, MAF sensor, Fuel pressure regulator, and the fuel filter.

Does anyone have any suggestions on what else it could be?

Thank you!
Jamie

TRITON7700

I Would Try The Idle Air Control Solenoid And/or Engine Coolant Temp Sensor. They Both Contribute To A Lean/rich Condition In The Fuel Regulation Sequence.

bagged94f150

mine says its the egr crap

Ford302V8

yea its the egr its not even worth fixing it wont effect anything just unplug that light

dewman

The light can come on for many different reasons, unrelated to the egr. Unplugging the light keeps you from knowing about future problems.

Smrtass498

Thank you to everyone for the replies. The bad thing about just unplugging the light is that the problem doesn't go away and with the light registering as being on, it won't smog! You used to be able to disconnect the battery so the light would go off for a while to get smogged, but DMV has got hip to that so now they can catch that and you still fail!

I took it to someone and they indicated my O2 sensors are bad. I hope this is it but when the light went on for the first time in 2003, I replaced the top two O2 sensors, and just replaced the lower one. Do they go bad that fast??? I sure hope this is it.....

Thanks again!

wde3477

Don't forget to inspect the sensor wiring and connections.

O2 sensors should last for several years, probably on the order of 100,000 miles or better - however, there are exceptions.

Your problem could be an actual condition as opposed to a sensor failure - some casual thoughts are - serious injector fouling, major vacuum leak, blocked EGR flow.

mippps

Jamie I have a 1996 f150 inline with the exact problem. Did you ever resolve the "checklight on" problem after all o2 sensors and max air flow valve were changed. I have changed all items except the 3rd o2 sensor. I do not know where it is. I changed the 2 on the exhaust manifold.

Thanks,
mippps

jetter2

Jesus christ glad to know I am not Alone!!

I have a 1996 F150 L6 2wd as well, and I have been battling the damn Check Engine Light for the past month.

I replaced all 3 O2 sensors, both pieces on the EVAP purge thing, and clean the Mass Airflow Sensors-god dang light is STILL comming on. I am running our of patience and Ideas. I will try to replace the Mass Airflow sensor next, well see if that does anything

jetter2

The 3rd one is under the truck just behind the transmission. Its real easy to get at, youll see it.