I've had DTC P0171 & P0174 (lean in bank 1 and lean in bank 2) for a few weeks now (check engine light cued me on it). Autozone scanned it for me. It's on a 2003 F250 SD 4x4 5.4L.

My first step was to clean the MAFS. Light came back on in about 30-40 miles. I then replaced the MAFS. 30-40 miles and the light came back on.

My first thought was disconnecting the battery wasn't resetting the comp and thats why the light was comming back on.

I went and picked up an Actron cheapy OBD II Scanner today at lunch. Cleared the codes with the scanner and drove back to work.

Checked the codes when I got back (no light on but was curious) and it shows P0171 & P0174 pending.

I've checked and the dipstick is seated properly. The hoses on the air intake appear to seated properly as well. The top hose is a pretty loose fit but it was seated all the way down. The top hose was oily. Not sure if this is normal or not. Could the loose fitting oily hose be the culprit?


Also, what is the lower hose? It comes off the back of the air intake and goes to the driver side valve cover. I know it's not the PCV hose as that is on the passenger side valve cover....right?

Any suggestion on where to go from here? Any help is greatly appreciated.

Sorry for the long winded 1st post.

 

Mine was trowing the same codes and I replace the hose on the PCV Value. 65.00 at the ford dealer.

 

how many miles is on your truck. it sounds like it could be O2 sensor(s)

 

I've been troubleshooting the P0171 code for almost a year now. I've cleaned then replaced the MAF, replaced the hose on the PCV (it did have a split), but it's still throwing the code. After all the reading I've done, my next step looks like the O2 sensor. Good luck, hope something works for you!

1999 F250 SD 6.8L V10, 146k

 

Make Sure the Hose is push on all tha way. You will here a pop when it is on. Try resting the computer and driving it for 25-75 miles and see if the light come back on. It took a week to fix my truck when it started doing that. But now it fixed. ('99 SD F-250 with 178000 miles on it)

 

Thanks for putting me on the right track for looking for a vacuum leak. I popped the hood and found the hose clamp on the upper boot of the K&N CAI kit loose and the intake tube popped out of the boot. I then found all of the hose clamps loose. I had installed the kit in the summer, and now all of the clamps are loose. (cold, stretch, loosening?)

Anyways,there was my vacuum leak. I wonder how much trash my motor burned up with the filter bypassed. My m/g might improve a bit?

Anyone else experience this problem with the K&N CAI hose clamps?

 

I have been fighting the code for a week now (I have a 2000, FWD with the V10). I have done all of th usually checks. Mine started out after I added injector cleaner to the tank? Soon after got the P0174. Now, I have both codes. Have made visual checks (didn't think a PCV is on the V10), cleaned the MAF, replaced the fuel filter. I don't want to spend the money to take it in yet. Is there a code reader that will assist with diagnostics?

 

well what about a lean code because of the EGR??

 

If it started after you put injector cleaner in the tank, it may be your ox. sensors, I have heard that alcohol will damage them. They sell those aftermarket, they should not be too expensive.

 

I have the same issue. Mine comes and goes. I have a hand held reader and when I clear the code it stays off for about 100 miles then comes back on. I'm leading towards an O2 sensor but I think these trucks have 4 of them and I don't know which one to replace or if I should do all of them.

 

it would be the upstream o2 sensors. if you get both codes, then the upstream on both sides.

 

By upstream you mean closest to the manifold? Right.

 

yep............

 

I am getting the same P0174 for both banks, i cleared them a few times now, i figured it was since i threw in a K&N filter on it, but nope it is still throwin the codes. Any ideas...both upstream O2 sensors?

 

That would be my LAST resort after everything else. What are the chances that BOTH Ho2's would be faulty at the same time. VERY unlikley. Not impossible, but have seen that very very few times. I can about guarantee its a vaccum leak somewhere that will affect both banks or possibly a MAF problem.


You need to look at your fuel trims and your Ho2 sensor activity.