Hi all, newbie posting. Went to the mountains in June, tried to go up a mountain too slowly I guess b/c check engine light came on but car was running fine. Recently, idle seems low at times, mostly when the A/C is turned on & in park. Today, I parked at the store & turned the steering wheel a little bit when in park & it acted like it wanted to stall. Got back home, put in park & turned the wheel again & it did the same thing. It hasn't completely stalled out but acts like it wants to. I am broke as a joke... no kidding. I don't know much about cars (or lingo so please spell everything out for me, try not to abbreviate too much), but I am up for a DIY challenge if needed b/c husband is out of town for 2 weeks. Code reader says P0171 Genertic System too lean Bank1

 

The P0171 may have occurred due to the high altitude. Try clearing your codes with your code reader, then check if the P0171 returns. Does your code reader scan any live engine data?

I'd stop by a parts store and have them test the alternator and battery to be sure they are ok.

If you have a volt meter, the battery should have 12.6 volts when the engine is not running and over 13 volts with the engine running.

The 05 engine has a belt tensioner with an arrow and scale showing how much tension it is putting on the belt. You owner's manual should have some pictures/info. You want to make sure the serpentine belt isn't stretched or worn out.

Here is a video on inspecting the belt/pulleys.

 

Thanks so much for your reply! I did clear the code & to be honest (maybe just paranoid) that seems to be when the very low idle & almost stalling started happening (also had oil changed & fluids topped off at that time too). It did come back on after about 2 days. I will take it to a parts store & have them check those things you mentioned. Does it sound like symptoms of a bad Idle Air Control valve? If yes, do you think it would be a hard job cleaning it or pricey to replace?

 

You will need to diagnose the problem before installing any parts especially since you mentioned that money is an issue.

The P0171 code is a too lean system that could be caused by a vacuum leak, weak fuel pump, etc...

You may need to read data from the engine computer, so can your code reader provide live data for O2 sensors, fuel trims, etc...?

 

Check for a plugged air filter, low idle eliminates a vacuum leak causing the P0171, probably not an IAC problem, if it happens when you're not moving and turning the steering wheel, I'd suspect a bad PSP (power steering pressure) switch. A weak fuel pump, plugged injectors or lean biased 02 sensor can also cause P0171.

 

I had the starter, alternator and battery check & all is fine there. While I was at the auto parts store, I went to back out of the parking space & turning the wheel the car stalled out. I put it in park & took the key out & sat for a few minutes, turned the car back on & backed out... there was still a little hesitation after putting it in drive & started driving. I can feel the hesitation the most when in park or stopped, when I turn the steering wheel or turn on the AC or having the AC running. When I am driving, the car is fine steering & the AC is on. The code reader I have doesn't provide live data. I will check the air filter this evening & research the other things you listed Dr. Drivability. Thanks so much for all the info!!

 

Dr. Drivability, I looked up the symptoms of a bad PSP switch & there are a lot of the same symptoms my car is having! Sometimes, when I ease my foot off the break I can feel a shift in the idle causing it to kind of jump or speed up & the stalling is similar of course. So far, that sounds like the best place to start for a $25 replacement part. Do you happen to know if the bad PSP switch would be the cause of the check engine code P0171?

 

The short answer, NO.

 

Follow up: I took the car to a mechanic that offered to check it out for free. After about 5 minutes he came back & said something was unplugged from the air filter & said I was good to go. (I didn't ask questions because he did that for free!) Whatever he did fixed the problem & even made the check engine light go off too.

 

Ah, sounds like you had a vacuum leak, and that would cause the P0171 in addition to your idle issue.

Thanks for verifying!