CEL and code P0171

[krbarnes]

My son's MSP threw a code P0171. After searching on this forum, it seems that the most likely causes are a vacuum leak and/or a faulty Waste Gate Actuator.

This afternoon, I replaced all the vacuum hoses. I started the car and took a vacuum reading directly on the port on the top of the intake manifold (around A in the picture). I was reading about 18" at idle. So far, so good. I reconnected the vac hose to the intake manifold, and disconnected a hose at the "T" connector (the junction that goes to the WGA and to the thing on the intercooler hose - around B in the picture). I was reading less than 5" here (the WGA is still in the loop).

It appears that I have a massive vacuum leak at the WGA (new hoses on it). Does it seem plausible that I need to replace the WGA? The car has just over 60K miles.

Thanks in advance.

 

[BOOSTR]

Some people have replaced their WGA. Test it to see if holds the pressure. Replace it with ATP unit if needed.

But that code that you list means that the bank 1 oxygen sensor detected too much oxygen in the exhaust. Could just be dirty or as you suspect a vaccum leak. I'd test the voltage and or clean it before replacing it.(O2)

I had a similar problem involving the second O2 sensor and it tested fine and I cleaned it with CRC quick drying electronics cleaner and the CEL has remained off.

 

[iluvmacs]

What voltage should the O2 sensor read? It usually fluctuates as the car runs.

Last time I swapped headers I used some air tool oil on the threads to help with the rusted O2 bung. It ran really rough for a while, and I didn't change anything to make it run "normal". It seems normal but I keep getting P0171.

 

[krbarnes]

I replaced the waste gate actuator, and now I'm reading 20" of vacuum everywhere. I cut open the old actuator, and the rubber bladder inside had about a 1" tear in it.

 

[iluvmacs]

I used the brake cleaner on the O2. After drying I took it out for a drive and it read <.2V before going dead (0V). I took the wiring apart and reconnected it and let it sit overnight. 50+ miles to work and errands, nothing on the upcoming CEL list, no CEL, and reading between .3 and .7 V as I assume is typical.

Thanks for the tip. I was worried the cleaner killed the O2 sensor, but it works great now.

New PCV valve too. The old one could come apart pretty easy.

 

[michiganspeed]

This could be my problem as well...had autozone read the CEL code and he said it was a bunch of things...including a vacuum leak...

 

[iluvmacs]

I just had some warranty work done to the VICS screws and I've only had this issue since they put the intake back on. I'm wondering if something is loose, not connected, or otherwise their fault.

Basically, if it's not a problem with the O2 sensor, I need to call the dealership and complain.

Thanks.

 

[iluvmacs]

It was a small vacuum hose causing the CEL. I found it and the problem was solved, so I didn't involve the dealership.