P0171 - Bank 1 to lean
- Thread starter StealthWyvern
- Start date
Yes that sounds like an exhaust leak. Your rich exhaust mixture is swapping places with the outside air, so your O2 reads lean, it dumps more fuel and you smell gas.
I had an exhaust leak on my manifold due to broken bolts but it never caused a code or driving issues. Your leak must be much more severe.
I had an exhaust leak on my manifold due to broken bolts but it never caused a code or driving issues. Your leak must be much more severe.
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- 03.5 YLW MSP
nope, no exhaust leak that im aware of. Now if I do its nothing like the ones i had before i swapped turbos and manifold. I had leaks all over the place.
RunAroundNekid
Member
Carbon deposit build up in the intake runners and valves.
Turbo cars are more prone to gunking. When the runners start to get carbon, it affects to the ecu's target afr. The ecu then adjsuts fuel to compensate for the altered air flow.
With that extra fuel the deposits break off, and it instantly sets a lean or rich code.
Simple checks to also look over.
Exhaust leak pre 1st o2 sensor.
Turbo cars are more prone to gunking. When the runners start to get carbon, it affects to the ecu's target afr. The ecu then adjsuts fuel to compensate for the altered air flow.
With that extra fuel the deposits break off, and it instantly sets a lean or rich code.
Simple checks to also look over.
Exhaust leak pre 1st o2 sensor.
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- 03.5 YLW MSP
Whatever it is I hope thats not it... I dont feel like yanking off the intake mani any time soon. Either way I dont think ill get a chance to look further into this issue tell i get another lovely issue looked at with my wonderful msp
I had the P0171 code also. It turned out to be a silicone coupler on my Injen was cracked. The one that connects the intake to the turbo. It was difficult to tell it had a crack until I removed it and squeezed the coupling. You might want to check that as most checks for boost leaks don't check the intake.
That was without relocating the MAF, correct?
I have the same code. 
Not sure what it could be so I am going to check the mani this next weekend.
Going to also spray all my couplers and hoses to make sure there is no leak.
Anyone done the spray of carb cleaner to see if they had a leak?
Thanks!
Not sure what it could be so I am going to check the mani this next weekend.
Going to also spray all my couplers and hoses to make sure there is no leak.
Anyone done the spray of carb cleaner to see if they had a leak?
Thanks!
Last edited:
RunAroundNekid
Member
I have the P0171 and a hairline cracked manifold and missing hardware.
******* moron who owned the car before me...
******* moron who owned the car before me...
My vote goes to either your throttle body problem being the cause or a torn vacuum hose somewhere around the engine. I had this code and discovered a torn vacuum hose was the culprit. It's definitely unmetered air being sucked in, not an exhaust leak. Bank 1 is your primary O2 sensor and if there's no leak at the manifold, it has to be unmetered air being sucked in.
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- 03.5 YLW MSP
I still havent had a chance to get a new TB in for the car and I haven't even started it up in over a week due to a bad turbo. Still waiting for all the gaskets and all that to come in to take care of it with another turbo.
Bluemica3.5
Member
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- 2003.5 mazdaspeed protege (Laser blue Mica) 2002 protege5
had the code over the summer and the 02 sensor was shot replaced then went away. until my stock mani started craking now its back.
slo03.5msp
Member
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- 03.5 yellow msp
It's an air leak past your maf before the exhaust side. I have chased this code twice. The first time being since the car was new for about three years. I was not that concerned about it since my wideband was reading fine. All said and done once it was smoke tested it was the egr, which will also lead to a poor idle. If you get this code and the car wants to die instead of idle I can pretty much guarantee it's the egr. Or a vaccum cap came off. But hey that's just what fixed my factory freak on stock internals for 8 years running 14lbs of boost. But I'm sure I probably don't know what I'm talking about. Search my handle you'll see all the threads I strated about it. I changed o2 sensors and mafs and this and that and it's just a hunk of s*** egr. That was recalled on all the 2003 p5's in a 2.0L but not the speed for some reason?!?!?!?!
Cool I will check the EGR also. This is like chasing a hidden rabbit in a field of 20ft tall grass. LOL Everyone had something a little different that fixed their issue.
I need to replace the o2 sensor because it looks horrible. What do you guys think of this one:
http://www.oreillyauto.com/site/c/detail/DPH0/ES20145.oap?keyword=oxygen+sensor&pt=02205&ppt=C0018
Or should I just get the one from the mazda stealership?
I need to replace the o2 sensor because it looks horrible. What do you guys think of this one:
http://www.oreillyauto.com/site/c/detail/DPH0/ES20145.oap?keyword=oxygen+sensor&pt=02205&ppt=C0018
Or should I just get the one from the mazda stealership?
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- 2002 Mazda Protege ES
I have the same code, comes on for a few days and then goes off for a while and then comes back, so on and so forth
