96 Aurora Code P0171

Hi everyone new to the forum here. I wanted to know what you guys thought about my current problem I'm having right now on my 96 aurora. That is the only code in the car. It means fuel system to lean bank 1. I have cleaned and inspected the mass air flow sensor. Cleaned it with electronics cleaner and took apart the peice were the metal cotacts are and sprayed them off. They weren't broke and actually looked new. I have a Green performance filter in the car and have read the oil on them can cause the maf to get dirty.

I also cleaned the throttle body out witch was so carboned up my tooth brush was sticking to all that black sticky carbon and oil residue. Now the gas pedal doesn't stick any more and idle is still the same after cleaning it at around 650 700. I used that syn power throttle body cleaner. Seemed to do a good job.

My symptoms are loss of gas mileage and power. The car's fuel gage is saying it's full when there is only like 6 or 7 gallons in the car. It likes to fire up also and stall right out in park. Then it will fire again and be alright. I also noticed after putting in the throttle body cleaner I took the car out on the high way to blow it out and it wouldn't go faster than 95. Didn't want to shift into 4th for some reason. I have a autobahn package and have been able to get it up over a 100 fast.

You have to drive it slow and it will catch the gears. Has a real hard time gettting up my hill when it's not warmed up. Feals like I'm runing on 1 cylinder but I'm not.

Don't want to confuse you all with these symptoms. Auto zone thinks it's the oxygen sensor or a vac leak.

Could any of you guys point me in the right direction. I'm pretty handy with doing maintenance on the car but no expert by far.

Thanks Jeremy

my first thoughts were same as autozone.... O2 sensor or a vacuum leak of some sort. How do plugs and wires look? Also, transmission problems accompanying throttle/fuel issues can be indicative of MAF sensor problems. Since your getting a lean code, sounds like your not getting enough fuel or getting too much air(i.e. vacuum leak). So, I'd check the fuel pressure regulator(just get a new one...cheap try for like $30) and also the air intake blow out door. On the passenger side of the air intake there is a spring loaded flap in case there is a backfire(so the intake doesn't blow into pieces). This can leak and cause a bad air/fuel mix. I had this happen to me. I was going through plugs and having hesitation issues.

Something else I just thought about. I would think an O2 sensor would have its own code too.

Ditto Zimaad

This is almost a standard response from me:

Check the basic, almost free stuff first:
FPR for sure
All vac lines (especially PCV valve and elbows)
replace PCV valve
be sure intake bolts are ALL tight
check that backfire flap
replace fuel filter

see how that stuff works for ya

now, a low power symptom (runs smooth but no power) could easily be fixed by one of the above. however, if the above things do not fix it you may want to look into a bad cat converter. a clogged cat can restrict the exhaust to the point where power is also restricted.


Fuel gauge is a different problem and common on the classics. Unfortunately it's likely that the fuel level sensor is bad. Unfortunate because it's integrated with the fuel pump and more than $300 for the part.

Thanks guys will do. I just had a full tune up done a few month back or so. I don't mean to be so crazy about all the symptoms but they are true. It's not me it's these cars. I have been fixing this one for 9 months straight off and on.

I expected alot better of a car with only 75k on it. Not perfect but better than 15 fixes in the last 9 months.

I might need a fpr. I drove the car to work this morning. My power is in like a surge mode. I press it down about half way or so and I get a ugly putting sort of back firing from the exhaust. Doesn't take off like it should. Feals like a V2 not a V8. Then it gradly starts to hit a high not and excelerats.

These cars when they have a problem I noticed not just one symptom but a handful of symptoms. It makes it hard to explain to others without confusing them.

Also my rpm were boucing around for about 5 minutes today when I wasn't gasing it just at a coast it was going from 1100 down to 500 and was just doing a bounce for about 5 or 10 minutes.

Thanks for the help. I 'll report back when I get something figured out.

you may also want to try some fuel system cleaner and isopropyl dry gas

the erratic rpm is also a symptom of bad fpr. Did you have to fuel rail replaced on the factory recall very important!!! extreme fire hazard !!!! But once the car is running right you will love it. Best car I have owned got a good one have had very few problems. (knock on wood) Try what has been suggested these guys here are great on solving problems with these cars. I have the factory manuals if you need anymore info will be glad to help.

Well I finally broke down and took my car to the cadilac dealership. They looked over it and said I had 18psi coming from the fuel pump module. Something like that. They want 625.00 plus tax and the 75.00 I paid for the diagnostics. My mechanic said 300.00 new. I also had a few miss fire codes and one for a oxygen sensor. But the guy said they were secondary codes and most likely the symptoms are from my fuel pump going bad.

It's really gotten bad over the last month. I almost didn't get it home from the place. Just wanted to leave my problem and possibly answer to this cause. I know it can be a real headache trying to solve a symptom on these cars.

I should be up and running strong again here in a few weeks. I need it inspected to so I'm probably looking over 500.00 to get it all done.

Thanks for all the help. I'll post back when things are all done.

I am curious about something. Before you decided to take your car to the dealer, did you take any of the advise, that was given by my fellow forum colleages? Or did you figure out that they were all wrong? And by the way, did you ask the dealer to guarantee. that their repair would fix your problem??

Yeah I checked the fpr was good. Cleaned the throttle body. Cleaned the maf sensor and also had my mechanic look at it before I decided to call them. When my mechanic couldn't figure it out and could only tell me I had a fuel problem I said f**** this and sent it in.

I don't know why your questioning me about it. If I can save a buck your damn straight I'm gonna look. But at the same time I am not a mechanic.

I didn't get a guarantee on the fuel pump but after a hr and a half of diagnostics that's all they could come up with. Sounds about right to me. Car seemed to be lacking the fuel it needed to run right.

Loss of power and almost can't get it to start. Also it dies on me when not moving. If you have to sit in traffic forget about it.

I take everyone's advice here seriously. These guys know alot more about the aurora than I do. But I'm getting there.

I remeber going through very similar problems with my olds 98 touring sedan and did the fuel pump with no improvement (hi-tech diagnostics and all). It would just die in the middle of an intersection with no warning.

'turned out to be the mass airflow sensor even though it didn't throw a code specific to the MAF.

If yer fuel gauge is wacky anyway then the fuel pump/fuel level sensor cant hurt.