tbunder wrote:
PO171
o2 sensor of (sic) maf? obdII says its o2 sensor, my dealer says maf.
Strictly speaking, what it means is this: The PCM sees, from the O
2 sensor reading, that the engine is running too lean, so it increases the fuel in the mixture. It sees that the engine is still too lean, so it increases the fuel some more. Eventually, it gets to the point where it's dumping as much fuel into the engine as it's allowed, and the O
2 sensor says it's
still too lean. Obviously, at this point, something is wrong, so it gives you the P0171 code.
I've been getting this, occasionally, on my own car. In my case, the problem is a connector, just under the front of the car. This connector goes flaky from time to time, blocking the signal from the O
2 sensor. I get P0171 when this happens, along with a few other codes relating to the sensor itself. I'm sure that if I took this car to a mechanic, and let him diagnose it, without telling him any of my own experiences, he'd diagnose it as a bad O
2 sensor, and tell me I need a new one.
My advice: Check the
connectors to your O
2 sensors, and maybe also to your MAF. If you've got access to a sufficiently-sophistcated OBD?II device [such as
this one] set it up to display, in realtime, a graph of your O
2 sensor and MAF activity. When my O
2 sensor connector craps out, the #1 sensor usually goes mostly flatline.
For more information, see my posting
over here.
