P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean
A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See possible causes for DTC P1130

P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit

The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

• Electrical:
• Short to VPWR in harness or HO2S
• Water in harness connector
• Open/Shorted HO2S circuit
• Corrosion or poor mating terminals and wiring
• Damaged HO2S
• Damaged PCM
• Fuel System:
• Excessive fuel pressure
• Leaking/contaminated fuel injectors
• Leaking fuel pressure regulator
• Low fuel pressure or running out of fuel
• Vapor recovery system
• Induction System:
• Air leaks after the MAF
• Vacuum Leaks
• PCV system
• Improperly seated engine oil dipstick
• EGR System:
• Leaking gasket
• Stuck EGR valve
• Leaking diaphragm or EVR
• Base Engine:
• Oil overfill
• Cam Timing
• Cylinder compression
• Exhaust leaks before or near the HO2S(s)

A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S

 

I've been having the same issues with the codes along with pinging after warmup.
Researching the codes P0171 and P0174 have lead me to this:
https://sites.google.com/site/fordf1...P0171P0174-Fix
This is exactly what I've been experiencing. I'm going to follow this and I'll repost what my results were.

 

I ran across same site. Doin mine upper plenum gasket and bolts next Saturday.

 

When you get the 171 and 174 codes is is most likely (never say never) that it is NOT the oxy sensors going bad but something happening like the MAF, air cleaner, vacuum leak, EGR valve. Doesn't make sense that both oxy sensors would be going south at the same time.

 

Guys, Thanks for all the information and advice. I had to take my truck in for an alignment, and while it was at the shop, I had them hook it up to their diagnostic machine. These guys are independents, but have 20+ years of experience at the Ford dealership, and they have the latest diagnostic tools. I told them to call me with an estimate of what it would cost to get rid of the trouble codes... Bottom line is my intake is leaking. The shop wanted almost $400 to do the repair. I decided to do it myself, and will be doing it soon using all FoMoCo parts. The shop owner gave me some good tips, and since I have built a few engines, believe I can do it with little trouble. The worst problem for me is reaching over the fenders to get to the engine... Wish me luck!

 

That fix I mentioned earlier seems to have done the job!