check engine light and codes

[midsouthgeek]

2001 explorer sport just over 60000 miles. Check engine light came on, off to auto zone I went. the codes were P0171 and P0174 (too lean bank one and two). does anyone know where i need to start? Should I do a tune up now? Thanks in advance.

Scott

 

[Donner]

Hi Scott...

It looks like because those codes refer to your vehicles' O2 sensors, that you have a few additional items to look at as well. Are you doing the tune up yourself?

 

[dogfriend]

Here is a thread with some info on P0171 and P0174. Those codes mean that the PCM is at the fuel trim limit and the mixture is still too lean. The most likely cause is a vacuum leak. Other causes can be fuel injector problems or other fuel supply problems.

http://www.explorerforum.com/forums/showthread.php?t=145587&highlight=p0171

 

[Donner]

Hi there...

Another in Carmichael... great place! That thread ended without resolution to the poster's questions, no?

 

[BrooklynBay]

Check # 51 in my list of useful threads for information on those codes: http://www.explorerforum.com/forums/showthread.php?t=177975

 

[midsouthgeek]

It looks like because those codes refer to your vehicles' O2 sensors, that you have a few additional items to look at as well. Are you doing the tune up yourself?

Yes I will do the tune up myself...

 

[Donner]

Excellent! I can't add to what you've already seen above, but I'll just say if you need to go at those O2 sensors, watch it! In my 96, there was one wedged up by the engine, split open my pinkie trying to get that one... didn't see it coming.

Hope you follow up on how things went...

 

[Turdle]

Yes I will do the tune up myself...

Don't replace the 02 sensors-or waste money on tune up parts--
The most likely cause of the code is leaking intake manifold gaskets. It would be rare for both upstream sensors to be bad. They are doing what they were intended to do, which is report an out of tolerance condition.

 

[Donner]

I thought that was implied here...

Here is a thread with some info on P0171 and P0174. Those codes mean that the PCM is at the fuel trim limit and the mixture is still too lean. The most likely cause is a vacuum leak. Other causes can be fuel injector problems or other fuel supply problems.

http://www.explorerforum.com/forums/showthread.php?t=145587&highlight=p0171

The first recommendation was to check for leaks and to look around. I don't think the intent was to have the poster buy all new parts, but check everything out first. Not being contentious, but I don't see where anyone recommended buying all new parts. I don't even see that a tune up was recommended...

 

[Redtrac01]

In my case, it was a partially clogged and cracked elbow in the PCV return line to the intake. I cleaned the tubes and replaced the elbow, which fixed my problem. You can check the O2 sensor output voltage to verify if those are working properly, but don't just replace them unless they're bad. My code list shows that O2 codes are from P0130 to P0167. It's probably not O2 sensors. Check all of the vacuum lines to eliminate them as the problem, before replacing the intake manifold gasket, which could be the problem.

 

[midsouthgeek]

Don't replace the 02 sensors-or waste money on tune up parts--
The most likely cause of the code is leaking intake manifold gaskets. It would be rare for both upstream sensors to be bad. They are doing what they were intended to do, which is report an out of tolerance condition.

How can I tell if it's the gaskets? Are they hard to replace?

 

[dogfriend]

How can I tell if it's the gaskets? Are they hard to replace?

You may be able to pinpoint the source of the leak using the trick in this post:

http://www.explorerforum.com/forums/showpost.php?p=1745282&postcount=4


There are at least a few writeups on replacing intake manifold gaskets on the forum if you search for them.

 

[midsouthgeek]

Well...

I looked for cracked hoses and visually inspected the intake. 60956 mile and It still looks really clean. I disconnected my battery and the code has not came back yet after a day of normal driving. I will watch it.

 

[midsouthgeek]

Code Has came back twice now. Guess I am getting my gaskets. Is there a recommended set? I only want to do this one.

 

[smaidens]

Hey Scott,
I just did my gaskets on my 01 Sport yesterday. I am not a mechanic and it took me about three hours. If you are fairly confident working on cars than you should have no problem doing it. I followed the steps from one of the posts on here and it was very straight forward. Unfortunately my light came back on with the same code as before (P0174) so I am still searching for a cause? Good luck with yours! Oh I bought the 00M12 kit from Ford for about $100 in Canada so it should be cheaper for you there (I think I have read around $50 -$60)
Scott