Lean Code, P0171

[GuyWithMazda]

Hello all, was wondering if anyone here ever had a lean code (P0171) issue. My truck has had it for a couple months and I have thrown many parts at it, but it won't give me a break. Any suggestions?

 

[Colin]

I have thrown many parts at it

What parts?

 

[rusty ol ranger]

Lean codes are usually a result of a vacuum leak.

 

[GuyWithMazda]

I have replaced the IAC, the exhaust manifold gasket, fuel filter, PCM, O2 sensors, temp sensor, previous owner replaced some of the emissions parts, timing belt, and PCV valve. I have taken it to a shop, and they said it has no vacuum leaks. I will be replacing the fuel injectors soon.

 

[Colin]

What brand of o2s? Should be bosch
What brands are the other parts?

 

[White_4x4Ranger]

maybe do a fog test.

 

[GCazares28]

Did you ever figure out the issue? I'm having the same issue with my 99 B3000. Replaced pretty much the same parts and still getting the same code, well (P0174); "System Too Lean Bank 2. Driving me nuts!

 

[sgtsandman]

Did you ever figure out the issue? I'm having the same issue with my 99 B3000. Replaced pretty much the same parts and still getting the same code, well (P0174); "System Too Lean Bank 2. Driving me nuts!

The original poster hasn't been back since March of 2024. So, chances are not good that he will respond.

That being said, when I had that issue, I ended up having to replace the catilytic converter on that side. Changing the O2 sensor didn't fix anything.

Also, as a preventative maintenance thing, O2 sensors are only good for about 10 years. So, try changing them out first and see what happens. If that is a no go, then it is catalytic converter replacement time. The Walker unit I bought bolted right up and has been fine for years, except for needing to reweld a section of the pipe at one point.

 

[Colin]

Any car I've had with that code has been fixed by replacing the o2 sensor

 

[GCazares28]

The original poster hasn't been back since March of 2024. So, chances are not good that he will respond.

That being said, when I had that issue, I ended up having to replace the catilytic converter on that side. Changing the O2 sensor didn't fix anything.

Also, as a preventative maintenance thing, O2 sensors are only good for about 10 years. So, try changing them out first and see what happens. If that is a no go, then it is catalytic converter replacement time. The Walker unit I bought bolted right up and has been fine for years, except for needing to reweld a section of the pipe at one point.

Thanks for the info Sgt. I'll try the o2 sensor next.

 

[GCazares28]

Any car I've had with that code has been fixed by replacing the o2 sensor

Appreciate the help Colin. Looks like that is my next step then.

 

[fixizin]

The original poster hasn't been back since March of 2024. So, chances are not good that he will respond.

That being said, when I had that issue, I ended up having to replace the catilytic converter on that side. Changing the O2 sensor didn't fix anything.

Also, as a preventative maintenance thing, O2 sensors are only good for about 10 years. So, try changing them out first and see what happens. If that is a no go, then it is catalytic converter replacement time. The Walker unit I bought bolted right up and has been fine for years, except for needing to reweld a section of the pipe at one point.

OUCH, how much does a new Cat cost? Isn't there THREE of them?

PS: was that a 3.0L engine and... shouldn't this be over in the engine forums?... NOT really a Mazda-specific issue...

 

[sgtsandman]

OUCH, how much does a new Cat cost? Isn't there THREE of them?

PS: was that a 3.0L engine and... shouldn't this be over in the engine forums?... NOT really a Mazda-specific issue...

It seems to depend on the year. Some have three some only have two. Mine has two. I cheaped out and bought a Walker replacement. Other than having to do a flange repair, with help from @lil_Blue_Ford, it's been holding on since 2018. $200 some vs around $600 for the OEM one.