Hello all,
I have browsed this forum since I bought my truck and have learned invaluable information. As I learn my truck, I will provide feedback as well.
I have owned this truck for a week. It has 128,000 miles. When I was driving home, the CEL came on. I ran the code and it was a P0171 code (fuel system lean). From what I have seen on here, an O2 sensor may be bad? Or vacuum leak? I have never checked a vacuum leak and I don't have any special tools. Where should I start? What is the easiest way to check for a vacuum leak? I can replace the O2 sensor but dont want to replace something that isn't broke. Also, the previous owner told me he replaced the bank 1 sensor not long ago. Any help would be appreciated. (I hope I posted in the correct forum.)

 

Welcome to the forum. Shamelessly copied the following from the website posted below:


A code P0171 may mean that one or more of the following has happened:

• The MAF (Mass Air Flow) Sensor is dirty or faulty
  Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
• There could be a vacuum leak downstream of the MAF sensor
• Possible cracked vacuum or PCV line/connection
• Faulty or stuck open PCV valve
• Failed or faulty oxygen sensor (bank 1, sensor 1)
• Sticking/plugged or failed fuel injector
• Low fuel pressure (possible plugged/dirty fuel filter!)
• Exhaust leak between engine and first oxygen sensor

A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:

• Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
• Inspect all vacuum and PCV hoses, replace/repair as required
• Inspect all hoses and connections in the air intake system
• Inspect and/or test the intake manifold gaskets for leakage
• Check for a dirty fuel filter and proper fuel pressure
• Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool
• If you have access, you may want to run a smoke test

Hope this helps.


https://www.obd-codes.com/p0171

 

My 96 Ram does not have a MAF.
I think I will start with the vacuums then o2 sensors. A couple questions about these.
What is the best way to identify a vacuum leak? I do not have a fogger or propane torch.
The owner claimed to change the o2 bank 1 sensor. I bet he used a Bosch. Could an OEM sensor fix the issue? The truck is running fine. Gas mileage seems to be very bad, however this is the first v8 I have owned. I filled up and drove highway most of the time and was at a 1/4 tank after 250 miles.

 

Need I say it?...

Check your plenum.

Some people use wd-40 to spray around to check for vacuum leaks. And I would try another new (NTK) O2 sensor.

 

Thanks for the help!
So...
I unhooked the negative battery terminal and replaced the o2 sensor with an NTK O2 sensor along with a new air filter. Hooked the battery up and started it up. NO CHECK ENGINE LIGHT. Great!. Then I walked around the truck and noticed my exhaust had spit out water and oil it looks like. I turned it off and turned it back on a couple times- same thing. I drove it down the road for a few miles and it stopped. Any idea what may have caused this?

 

Not sure about the oil part but it is normal for moisture to condense in the muffler as it cools. Then it gets spit out on the startup.

 

And the oil may not even be oil. Might just be soot discoloring the water......