Car running too lean?

[MSP818]

I have a completely stock 03 msprotege and I went to get my smog test. It failed. The check engine light came on while he was smogging it. So i took it to my mechanic and he tested it and told me the car is running too lean. Any idea on how to fix this? He also gave me the code after testing it and its P0171 System Lean Bank 1. I'm not sure what that means. Any help would be greatly appreciated. I need it to pass smog so i can get my 2010 reg stickers on my car! Thanks

 

[sephiroth]

02's, injectors, fuel filter, fuel pump and spark plugs, I'd try plugs first.

 

[ucMP3]

plugs, O2 sensors (probably primary) are first things I would check/replace. then run some fuel system cleaner thru your tank a couple times and reset the ECU.

 

[JCell]

maybe a vac leak

 

[BOOSTR]

that code could also mean a ruptured WGA in addition to the other possible suggested causes.

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[Bluemica3.5]

just had this code. changed front o2 sensor per dealership , went away then came back on , found out it was a cracked vac line. bad stock plastic vacline

 

[mini_FD]

I just got that code today.

probable cause i was told is low fuel pressure, large vacuum leak, dirty defective MAF sensor, engine mechanical condition.

i threw the code after i filed her up on a full tank today.

 

[fruitbane]

2000 Protege ES with similar problem

My 2000 Protege ES has developed a similar problem. It's getting a "lean exhaust" code that occasionally goes out for a few days but inevitably comes back. My mechanic says what he's read indicates the likely culprits are the air intake and the mass air flow sensor. He poked around the intake while watching some measures and everything seems OK there and he cleaned the MAF sensor. It took less than 24 hours for the light to come back on.

My mechanic wants to replace the MAF sensor (expensive part, at least for him to order from a dealership). Are there any other cost-effective avenues I should encourage him to pursue first, or cheap sources for Mazda MAF sensors?

Thanks, all.

 

[pavone]

i would try cleaning the maf first before replacement...worth a shot and cost nothing but time if you have some brake cleaner lying around

 

[dEd hOm E]

check all the vacuum lines and intake gaskets for leaks. 9/10 i see p0171 for vacuum leaks. easy check is to have car idling and slowly spray over any possible vacuum leak(vacuum lines, WGA, intake manifold gaskets) with some break cleaner. if there's a leak the rpm's will fluctuate slightly. or if you have access to an OBD scanner with datalist/datalogger watch the short-term fuel trim

 

[fruitbane]

So, my mechanic cleaned the MAF and that didn't fix the problem. Turned out to be the intake gasket. Welp, another lesson learned. Thanks.

 

[jcritt03p5]

I am having the same system bank lean code in my 2003 Mazda protege 5, it started when I had an AEM short ram CAI installed, also had a Large evap emissions leak code as well, but i put my stock intake back on and i only get the lean code now, I have new plugs and wires in but still shows up, I have a scan tool and use to reset the code and it would be off until about half a tank then turn on over and over again, but now if i reset it it will turn on again before i shift to 3rd gear. can anyone help me out?

 

[Jo060]

02's, injectors, fuel filter, fuel pump and spark plugs, I'd try plugs first.

I don't think the '01-'03 Protege have a fuel filter, unless you count the one in the tank.