Trouble shooting p2196 engine lean error

[Stubek]

I have a p2196 error on the pre-cat O2 sensor. So, engine is running rich. What can I do to trouble shoot this? Are the pre- and post-cat O2 sensors the same? Can I swap them and see if the error is still there? What else would cause this?

[V2Rider]

Taken off the "web" :)

The P2196 fault-code means that the on-board emissions-monitoring system is reporting a rich fuel mixture via the 02 sensor in the car's exhaust. However, if you're also seeing black smoke emitted from the exhaust, that could indicate that you may have a bad/failing fuel-injector that is flooding a cylinder with too much fuel. Interpreting the engine fault-codes is something of a "black art"; you have to consider all observed symptoms as well as all reported fault-codes and correlate this information in order to arrive at a rational prognosis.

If you really want to pursue this as a DIY repair, you really need to acquire a copy of the Bentley Service Manual for your car so that you can properly interpret the fault-codes and to have a fully-defined repair procedure.

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