P0171 code…

I had a check engine light come on the other day P0171. I have had absolutely no issues with my truck (just drove from NC to VT and it starts/runs fine with great MPG).

It initially came on before the trip and I notice a small hose was disconnected. I reconnected it and the light turned off. Now, about 600 miles later, the light came back on but the hose is still connected. Still no performance issues. Not sure what’s going on!

 

What year truck, what motor, mileage.

Running lean... anything that can upset the air fuel ratio can cause this. Easiest is to check for vacuum leaks, you found one. Get a can of carb clean/brake clean and while the motor is running spray around the intake, listen for any RPM increase/decrease, if there is one, investigate. Spray around the MAF and airtube. You can take the MAF sensor out, you might have to buy a tool to undo the screws, get a can of MAF cleaner and spray it off, let it dry and reinstall. Unless you find something obvious like a vacuum leak getting her fixed might take a few trys. If you cant find anything obvious things to consider in the future would be a front O2/AF ratio sensor... depending on the year/motor combination, a brake booster vacuum leak and even a fuel pump.

 

The same hose you reconnected may have a split in it. Hoses do deteriorate over time and need to be replaced.

While your profile nor your post tells us what you are driving, being in the 1G forum indicates you may be at least 20 yo at a minimum. That's getting where rubber parts (all of them) are long in the tooth if still OE.

 

I guess somehow my profile dropped the info somehow… 1996 V6, 4x4 base model

 

IIRC the 96 MY has a vacuum operated "idle up" swith on the Power steering, that is an easy one if it is that.

 

I had that code recently and it was a bad brake booster causing a vacuum leak. Replaced it and code is gone

 

I'm wondering if there is a clog or something that caused a build up of pressure leading the hose to come off. How would I go about testing that? Fixing it?

 

Verify you don’t have a vacuum leak and hop over to the fuel delivery side. Berryman b12 made mines go away. May be faulty fuel pump or injectors or something blocking fuel flow.