code 0171 left bank lean

ttabboo · #1 (**permalink**) 08-10-09, 03:33 PM

I have a 2000 Catera with 43,000 miles. I keep getting a left bank lean code when I take it to autozone. I looked for vacuum leaks & found a line off near the MAF so I put it back on, I also put a new fuel filter in just in case since I read in other posts it could be that. the light went off for a couple days now it is back. The car seems to run OK even though the light is on. I have also pulled out the MAF and cleaned it with electronic parts cleaner, that seemed to help for a few days but light came back on same code. I have only the left side code but not the right or I would go ahead and replace the MAF.
Anybody have any suggestions on where to head next. I hate to take it to a garage and pay for every wrong guess they make.

R-Caddy · #2 (**permalink**) 08-10-09, 07:33 PM

Man, that is one of my problems as well. I have 2 '97 Cateras, so I tried swapping different parts- MAF, CPS, plug wires, coil, but the problem still exists. Gas mileage went to $#!t Even checked the timing belt, but it seems OK. As soon as some bright idea hits my skull and I figure it out, I will update you.
Good luck til then
Aras

CateraMV6 · #3 (**permalink**) 08-10-09, 07:39 PM

I have 130K on mine and it came just before my 2200mi trip, I reset it with my scan gauge... then it came a few hours later... probably due the fact that I put some 87 in it... then it was gone all the way until the trip back and it came at a random time during acceleration... same deal I reset it again and it hasn't come back yet...

I think its the MAF sensor getting glitches in the system because the car ran fine and averaged 27mpg... so... maybe see about replacing the maf sensor...

ttabboo · #4 (**permalink**) 08-13-09, 08:20 PM

Just an update I now have 0171 & 0174 so both banks are running lean. I think maybe MAF is going bad car seems sluggish. Found MAF at Amazon.com $139.05 shipping free.

OpelOmegaB · #5 (**permalink**) 08-15-09, 03:30 PM

Hi,

I just got codes 171 and 174 in my 2000 Catera Sport.
It has now 107k on it. I have NOT changed the O2 sensors yet. Does anybody know if that might have triggerd the CEL?

Car runs perfect as it always did in the last 4 years and 73k miles. I never used premium, only 87 octane. I don't think it has anything to do with a bank running lean.

According to German Opel info, the 3.0l V6 can run on regular gas (which has less octane in Germany than in the US) if you don't use full power all the time. Driving 85 or 90 mph on CA freeways is definitely NOT using full power.

Best regards

Hans

ttabboo · #6 (**permalink**) 08-15-09, 11:02 PM

Cleared codes & both 0171 & 0174 came back so I am going to try new MAF since I cleaned it twice and it didn't fix the problem. I will post update when I get new MAF. This has worked for many people according to old posts on this forum.

Sontov · #7 (**permalink**) 08-19-09, 06:08 PM

hey quick question: If you're running too lean, and im running [System Running too Rich] with codes po172 (bank 1) and po175 (bank 2)... is this the same 'MAF' sensor prob?
Sontov

ttabboo · #8 (**permalink**) 08-26-09, 11:07 PM

I got the new MAF 139.00 at Amazon.com shipped to house. I installed it, drove the car and after driving it next time I started car the CEL cleared out & all is well. Yes I think this will also work with a rich code on both banks since it is just the reverse of same problem.

CateraMV6 · #9 (**permalink**) 08-27-09, 03:08 AM

I got mine to show that code a couple times... last time I tried brake cleaner on the sensor itself, I soaked it a few times to make sure i cleared all of the crap that could have gotten on it and as a result its been 1000mi without the light so if that didnt fix it next will be the MAF sensor.

On another note my father is a car mechanic and he is 100% certain that its caused by low fuel or vaccum leak.... notice how it always says left bank lean... meaning the one farthest from the fuel pump... and also if you look at the engine both fuel lines feed in from the passenger side on the manifold so as a result the driver side or left bank is not getting the proper fuel if your fuel filter is dirty.

If you have a vacuum leak its best to take some sort of cleaner, brake or carburator, and try spraying around the engine. If you get a spike in the RPMs then you will know where it is.

As for fuel use it says 93 or Higher only... the motor is 10:1 compression so you must run the proper fuel type, otherwise the car adjust its spark and then you end up wiht a detuned motor that doesnt make peak power where it should... such as in the mid range for max torque...

...then you end up mashin on the gas peddal more often and as a result you use more gas so your savings of 2$ at the pump turn into something like 5-6$ wasted in poorly performing car.

The car is nearly 4000lbs and it needs every ounce of power to make it move.

ttabboo · #10 (**permalink**) 08-31-09, 01:20 AM

The reason it is the MAF instead of fuel is the MAF is giving the wrong info to the computer so it give a lean condition.
for some reason it shows up 1st on the left bank but will soon progress to both banks. When it does this it is good indication it is a bad MAF. You should also replace the fuel filter 1st just in case it is a fuel starvation problen & also check the fuel pressure before laying out the cash for a new MAF. I hope this helps.
It is also possible a vacuum leak can cause this peoblem if it doesn't progress to both banks.