Need a little help here. First the specifics-2002 f150, 2wd auto 4.2l, 69,000 miles. Got a code p1151 which only says it is a manufacturers code for improper fuel air mixture. Truck is not running different, fuel economy may have decreased but it is ten degrees here so I have been letting it warm up. So it is hard to tell if the economy is down or if it is from letting it warm up. I reset the code and it has not come back but I have only driven about 45 miles since I had the code read and reset. Has anybody had this code before and if so what sensor was bad. As just about any sensor could disrupt the fuel/air mixture and it is hard to tell what sensor may be bad or going bad because the truck is not acting any differently. Thanks for any help you may be able to offer.

T. Roberts
UFD Local 1147

 

have someone check the o2 sensors with a scanner, also check the egr. hopefully u dont have an air leak around the intake. try (carefully) spraying a fluid like brake cleaner lightly over the intake hoses and plenum to see if the idle changes. don't spray alot and listen closley, but be very careful and try to stay away from the filter. sometimes u can find a leak or vac line off quite quickly. again use extreme caution and spray lightly taknig note of where the "stream" is.

 

I would start by cleaning the MAF. This is what mainly controls the A/F ratio. Also check the PCV hose elbows for cracks.

 

Of the few codes I know by number, I know that the p1151 code means, and if I remeber it right word for word, 'lack of HO2S switch, sens. indicates lean. Bank 2 Sensor 1'. Back when my computer threw this code, I replaced my HO2S and my truck quit with the codes. HO2S is short for Heated Oxygen Sensor. Bank 2 is the driver's side exhaust coming from the engine. Sensor 1 is the pre-cat sensor. Try replacing that O2 sensor and clear your codes before you start your engine. Also, it is a good idea to disconnect your battery while you swap out the sensors or for at least 20 minutes to allow your truck's computer to reset itself. Good Luck to ya

DRP