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To start, I have a 2006 e-350 5.4L that had an engine replacement done last week. The engine was replaced with a reman engine and during the drive home (13 hours) I got a check engine light which was showing codes P0171 and P0174 for bank 1 and bank 2 running lean.
The shop said it may be the engine "breaking in" and to monitor it over the next few hundred miles, but I don't really buy that.
I'm trying not to think about worst case scenarios this early in the game, but what would some likely possible causes for these codes be? Since it's Bank 1 and 2 I'm assuming that the air mixture is off but I figured I would reach out to people who are more familiar with these vans.
Any help would be greatly appreciated!
EDIT: the van has 79K miles on it.
Last edited by ryannimmo; Sep 17, 2015 at 08:07 AM.
Reason: Info
Vacuum leak? - look at the PCV elbow on the back of the intake. Easy to change on a van, real PITA on a truck. Solved a CEL on my 97 van for too lean both banks.
Dirty MAF? - especially if you use a K&N filter since the oil mucks up the MAF - cleaning MAF solved too lean both banks on my 96 Crown Vic
Other ideas:
Air leak after MAF?
Exhaust leak before O2 sensors? - had this problem on an OBD LT1 Buick Roadmaster
You'd hear an exhaust leak, I think that's a highly unlikely thing.
I think it's more than likely a vacuum leak of some flavor. How does it run at idle? Don't buy their excuse, brand new vans don't throw codes as they break in. Yours shouldn't either.
No pictures in the thread. I think I have a good one on my other computer.
The elbow is on the back of the intake. If you pull your engine cover, it's very easy to see and replace. One of the few engine related things easier to do on a van than a truck.
I cleaned the MAF sensor with the cleaner (5 or 10 sprays) and the light stayed off for 10 or so minutes of driving and came back on after I turned it off and cranked it again.
Not hearing any loud exhaust ticking or anything (thankfully)
Any votes for just going ahead and replacing the O2 sensors as well?
I'd vote that way
What you could be dealing with is, the original engine died, you replaced the engine with a re-man, when the old engine died, what sensors did it take out with it???
Even thought you had the engine replaced by a professional service, their start-up, and test worked fine, but after your journey home (and 13 hours is a tough "break-in" on a re-man) some of the sensors could have been effected by the old engine blowing out. You going to have to start replacing senors as they show up.
Also, your codes should be=
171 - Fuel System At Adaptive Limits / No HO2S Switching Detected
174 - HO2S Switching Time Is Slow
I'd vote against replacing the oxygen sensors without some more diagnostic work. You're showing lean codes for both banks, so unless both oxygen sensors happened to die it's not them. I've never seen a broken valve cover like that, how'd that happen? You can check the waveform for the sensors with a good scan tool or oscilloscope. You can also pull the sensors to see if they got coated with oil.
Originally Posted by Wildman25
Also, your codes should be=
171 - Fuel System At Adaptive Limits / No HO2S Switching Detected
174 - HO2S Switching Time Is Slow
That points right to the O2 sensor.
Those codes are really old! EEC-IV was the OBD-I system used from the mid-80's to 1995. They don't apply to anything newer than that.
