Dtc P0171

[daejuanj]

Hi all,
I got this code after failing an emissions test. I've searched these forums, and found out what the DTC P0171 means. But I want a little help in what needs to be done.

The car has a weird noise to it, almost sputtering sound. I found out it was coming from a hole in my muffler/resonator.

Now, I've had electrical problems in this car before (defective MAF sensor), but I'm wondering (hoping) the hole in the muffler would give this error code.

The weird thing is, the SES goes off and on. When I took it to a dealership, they couldn't diagnose it, because the light was off and told me nothing was wrong with my car.

Just looking for a little help. I'm going to take it to a friend who owns a shop so he can fully diagnose it.

Regards

[richtazz]

P0171 System too Lean (Bank 1)

This is a generic code, and could be caused by many different things including a partially clogged fuel filter, vacuum leak, worn throttle body, borderline oxygen sensor, etc.... It's a very difficult code to properly diagnose, as not only one component can cause it.

[daejuanj]

Originally Posted by richtazz

P0171 System too Lean (Bank 1)

This is a generic code, and could be caused by many different things including a partially clogged fuel filter, vacuum leak, worn throttle body, borderline oxygen sensor, etc.... It's a very difficult code to properly diagnose, as not only one component can cause it.

I was afraid of that.

Could a hole in the muffler/resonator cause this? I just want to start pricing my repair now before I get it fully diagnosed.

Thanks for the reply.

[richtazz]

Since the muffler and resonator are downstream of the catalytic converter and oxygen sensors, I'd say no. The front o2 is what determines if the system is lean or rich, so it has to be an issue on/in the engine itself. If it's the GTP in your signature, have them check both the lower intake gaskets and the supercharger base gasket for vacuum leaks first, as these are areas known for causing a lean condition.

[daejuanj]

Originally Posted by richtazz

Since the muffler and resonator are downstream of the catalytic converter and oxygen sensors, I'd say no. The front o2 is what determines if the system is lean or rich, so it has to be an issue on/in the engine itself. If it's the GTP in your signature, have them check both the lower intake gaskets and the supercharger base gasket for vacuum leaks first, as these are areas known for causing a lean condition.

Ok, now I'm getting a little worried.

About a month ago I had to have the lower intake gasket & supercharger gasket replaced. Think the dealership could have did a bad job with those tasks? The thing is, they wouldn't replace the valve cover gasket without an extra $115, so I declined. The SES starting coming on about a week after I picked it up from the shop.

Also, I notice at idle, the motor shakes in a odd manner.

What's weird now, is that the SES light is off. But it'll come back on soon I suppose, like it's been doing.

[tblake]

did they replace the injector o-rings? I would just start looking for a vacuum leak

[daejuanj]

Originally Posted by tblake

did they replace the injector o-rings? I would just start looking for a vacuum leak

I have no clue. They are so vague on what they do. You have to drill them for information.

I'm going to call and ask them after work.


Also, I have to pass the emssions test to renew my license plate registration. If the SES light isn't on, could I pass the test?

[BNaylor]

Originally Posted by daejuanj

Also, I have to pass the emssions test to renew my license plate registration. If the SES light isn't on, could I pass the test?

To pass the odb-ii 1996 and up emissions test in most states that require it you have to get an emissions (IM) readiness flag as being OK. IM status will be checked by the scan tools they use. It is possible to get a IM status OK without the SES/CEL light on but certain DTCs will inhibit IM readiness and cause it to fail so you may flunk inspection again. I have a better than average odb-ii scanner and check IM status right before the annual emissions test in Texas just to be sure it is good.

Why were the supercharger and LIM gaskets replaced and with your low mileage? The P0171 DTC is one of the worst to get and may involve alot of controlled substitution of suspected parts and diagnostics.

At least on the front valve cover gasket you can now get that replaced free of charge.

See link below.

http://www.automotiveforums.com/vbul...d.php?t=893778

[daejuanj]

Originally Posted by BNaylor

To pass the odb-ii 1996 and up emissions test in most states that require it you have to get an emissions (IM) readiness flag as being OK. IM status will be checked by the scan tools they use. It is possible to get a IM status OK without the SES/CEL light on but certain DTCs will inhibit IM readiness and cause it to fail so you may flunk inspection again. I have a better than average odb-ii scanner and check IM status right before the annual emissions test in Texas just to be sure it is good.

Why were the supercharger and LIM gaskets replaced and with your low mileage? The P0171 DTC is one of the worst to get and may involve alot of controlled substitution of suspected parts and diagnostics.

At least on the front valve cover gasket you can now get that replaced free of charge.

See link below.

http://www.automotiveforums.com/vbul...d.php?t=893778

Thanks for your reply.

Upon taking my car because of it misfiring.
They inspected it.
1.) MAF sensor was replaced due to it being defective.
2.) #1 coil was replaced, cause of misfire.
3.) Supercharger gasket was leaking coolant
4.) LIM gasket was leaking

[BNaylor]

Were these external coolant leaks or internal where coolant was being consumed in combustion?

[daejuanj]

Originally Posted by BNaylor

Were these external coolant leaks or internal where coolant was being consumed in combustion?

I'm not exactly sure.
This is something else I'll have to ask them. Talking to these guys is painful.


I just called them, they're telling me the code could be a defective cat, or gas cap leak.

I'm more inclined to take you guys advice, as it seems they are trying to cover themselves from what they did wrong on their work.

[BNaylor]

The reason why I asked is to to determine if any action should be taken on the front 02 sensor since this component can set off the DTC. It may have been contaminated with unburned coolant going out the exhaust. Unburned coolant could also damage the CAT convertor. Proper 02 sensor diagnostics requires that the 02 sensor be checked for proper operation with a scan tool. 200 to 800 mv (.2 volts - . 8 volts) and to make sure it is not lazy.

I don't believe the P0171 DTC is a result of a large leak in the evaporative emissions system (Gas Cap Code). Plus you would have a DTC related to that.

I would explain to them the SES/CEL light with the P0171 DTC came on within a reasonable period of time after their work and demand warranty action.

Plus if the CAT is bad it should be replaced free of charge since there is a notice about it for 2001-2002 models. Notice is at our Tips & Maintenance forum.

http://www.automotiveforums.com/vbul...d.php?t=681283

[daejuanj]

Originally Posted by BNaylor

The reason why I asked is to to determine if any action should be taken on the front 02 sensor since this component can set off the DTC. It may have been contaminated with unburned coolant going out the exhaust. Unburned coolant could also damage the CAT convertor. Proper 02 sensor diagnostics requires that the 02 sensor be checked for proper operation with a scan tool. 200 to 800 mv (.2 volts - . 8 volts) and to make sure it is not lazy.

I don't believe the P0171 DTC is a result of a large leak in the evaporative emissions system (Gas Cap Code). Plus you would have a DTC related to that.

I would explain to them the SES/CEL light with the P0171 DTC came on within a reasonable period of time after their work and demand warranty action.

Plus if the CAT is bad it should be replaced free of charge since there is a notice about it for 2001-2002 models. Notice is at our Tips & Maintenance forum.

http://www.automotiveforums.com/vbul...d.php?t=681283

Hopefully when I take my car to get it fully diagnosed we're find the problem. And no, I highly doubt it has anything to do with my gas cap either. That was the first guy I spoke to at the dealership, the second guy mentioned a bad cat.

I did notice, what appears to be dried coolant on the front headers, around the gasket. I'll take pictures when I get off of work.

[daejuanj]

I had the cat replaced, and the resonator removed, still same problem.

I also forgot to mention initially in this thread, I've felt the car to be a little sluggish.

I'm going to replace the fuel filter and PCV valve either today or this weekend. I'm also going to try and find a vacuum leak around the gaskets. If that doesn't work, I'm going to try and take a look at the o-rings.

Any tips on getting to, and replacing the o-rings, and possibly cleaning the injectors?

[tblake]

the injectors arent so bad to replace on the 3800. Make sure you coat the new ones with grease so they slip in easy.

I'd just grab a can of carb spray and start spraying at things listening to see if the RPM increases.