Scotty;
Today my trailblazer threw a code at me, it is P0171. Looking online at stuff, there seems to be a few issues it can be. Possibly the MAS sensor, O2 Sensor Bank 1, or possible fuel injector stuff. It has been running well with no issues until today. I am quite familar with the engine per watching your videos on maintenance! I have a scan tool that can show me live data too if needed. What would you recommend? I would love for it to be a quick sensor swap but may end up in a shop. I have cleaned the MAS sensor twice, erased all codes, and it came back immediately. Suggestions? Thanks!
Thanks everyone for your help and advice! I went back through everything today and double checked the integrity of all the hoses and connections. Thankfully all hoses and connections were in excellent shape. I did however, come across a hose connection point on the air intake part of the engine that looked like it was missing it's small little thumbnail cap. I remember noticing it before thinking it was an odd thing. Sure enough, the cap had fallen down in between the engine during cleaning and I forgot to put it back on! Doh! I got it snugly back on and everything is fine now. Fuel trims are back to normal. My gosh, what an important litlte cap, so silly. {black}:crazy:
Some suggestions here:
https://www.way.com/blog/how-to-fix-a-p0171-code/
https://axleaddict.com/auto-repair/Trouble-Code-P0171-and-P0174-Diagnostic
Thanks for your input! I double checked all my hoses and air system, everything looks good. I went to the auto store and got a new MAF and installed it. The check engine light is off and the vehicle seems to run normally. I did plug my ODB computer back in and found the code is still there and the STFT B1 and STFT B2 are both still adding fuel, betwen 25% and 35%. I can't imagine I have a vacuume leak. With my engine light off, does this mean the system is needing time to recalculate everything with the new MAF sensor?
the code is still there and the STFT B1 and STFT B2 are both still adding fuel, betwen 25% and 35%.
Live data is what's happening 'right now', hence "live". And 25%-35%, that's too high.. So, you're either getting too much air or not enough gas.
found the code is still there
did you clear everything after replacing the sensor?
needing time to recalculate everything
yes it needs to calibrate
I can't imagine I have a vacuume leak.
I can. Easily, on a 14yo vehicle.
