1998 Ford explorer EB edition Wont pass smog

[lancer5717]

I just bought my 1998 Ford Explorer Eddie Bauer edition and i went to smog it and it wouldnt pass. The smog place gave me a paper that had a code on it and some also said a few other things but i didnt understand what it ment.

It said: P0171, System to Lean, Bank 1.

I think that it has something to do with my o2 sensors so i bought one but when i went to put it on there was 4 o2 sensors. Does anybody happen to know that code means and what O2 sensor it is that i need to replace. I know that there is one sensor before the cat on both right and left as well as one aft of the cat on both right and left Exaust pipes. but i dont know what one it is

 

[bobflood]

System Too Lean could be several things, of which an O2 sensor is only one. Bank 1 is the passenger side of the engine. Which engine do you have?? The SOHC V6 is well known for intake manifold leaks, which can result in that code. You, or your mechanic, need to do some analysis work before you start throwing parts in. Good luck.

Ok - just noticed that you have the 5.0 V8. Less likely that it is intake manifold, but still possible. Also, look for vacuum leaks is all of the vacuum hoses - any place that allows "unmetered" air (air that comes in behind the MAF) could lean out the mixture.

 

[1992fordgreen]

id replace all 4 they probably go out at the same time.

 

[bill06447]

Vacuum leaks the most common cause of this code, also EGR system leaks...the O2 sensor is just the poor messenger, the things just analyze the exhaust gases and tell the computer to adjust this or that. They are super dependable but take the blame for everything that causes them to give lean or rich readings. Do a search, this issue generates a thread about 3x a month...

Bill

 

[Tbars4]

..Welcome here..

..Reasons for a p0171...

A) Not the o2 sensors

1) Probably Vacuum leak
2) Clean the MAF
3) EGR tube leak
4) Plugs and wires

OR 5) Intake manifold gaskets..

..Another vacuum area to check is the brake booster grommet..