2001 Ford Explorer Sport code: P0171 Bank 1 too lean

S4patrick · 09-24-2007, 08:07 AM

Hello....

My 2001 Ford Explorer Sport 4x4 (133,000 miles) CEL (check engine Light) came on over the weekend.

ONE CODE came up, P0171 Bank 1 too lean.

Is this a bad Primary o2 sensor?

I believe that Bank 1 is the Driver's Side?

Any good places to buy a replacement o2 sensor?

Any other possibilitiesof why the CEL has come on?

Thanks everyone!

jonmark1985 · 09-24-2007, 10:39 AM

could be a bad 02 sensor, could also be:

bad intake gaskets
vaccum leak
bad injectors
bad ecm
broken wiring

I would reccomend checking for vaccum leaks first. Its cheap and its easy, when compared to changing the oxygen sensor, or any other part for that purpose.

I'd also reccomend a genuine Motorcraft oxygen sensor, rather than a bosch or borg warner unit.

TonyD · 09-24-2007, 02:50 PM

My 99 Explorer had the same code combined with 174 (right bank lean). Turned out to be the intake maifold gaskets. On the 4.0, SOHC engine they were pretty easy to change; both the upper and lower gaskets came in the set I got at Checker for about $24.

S4patrick · 09-26-2007, 09:01 AM

Hello....

Thanks for the reply....

you say to check for vaccum leaks first.....can you tell me a little more about this?

What to look for? What areas?

Any additional information is greatly appreciated.

~Patrick

tequlia is good · 10-27-2007, 01:34 PM

Hi guys,
My CEL light came on over the weekend on my 97 explorer. Took it to local garage, turns out I need the INTAKE GASKETS and the HEGO SENSORS REPLACED. I was quoted £1000 uk stirling (2,000 dollars) for the repair, looks like I will have to drive it to a breakers yard But that serves me right for living in london