how 02 sensors work
p0174 tells me system too lean on bank 2
Now before you run off to the store and buy an oxygen sensor, this may or may
not be the problem.
Oxygen sensors work by generating up to 1 volt of electricity.
The richer the condition the closer you get to 1 volt. The leaner you get the less electricity it generates, to as low as 0 volts. Oxygen sensors jump around in voltage constantly. The processor is only looking for the mean value. So if it is jumping around 450 +/- and 700 +/- millivolts this will probably satisfy the processor. If it falls out of this range the processor will make a fuel dwell, timing or iac adjustments to name a few.
Where to start. I would check and see if you have a vacuum leak somewhere in the vacuum lines. Then I would check to see if there is a leak in your vacuum break assist unit If your model has one. Are the breaks working well ? or has the pedal changed in feel ? Intake manifold leaks, plenum leaks.
Another area to check is fuel delivery. Are the injectors performing properly ? is there good fuel pressure and supply ? just good pressure doesn’t mean you have good volume.
When was your last tune up ? Was this unit just recently worked on before the problem occurred ? What was happening just before you noticed the light was on ?
I hope this helps……………………
