Both are related to problems with B1S1 air-fuel ratio sensor. It does the same job as an O2 sensor but it works differently. Bank 1 or B1 means this sensor is on the same side of the engine as cylinder #1. Sensor 1 or S1 means this is the first sensor in the exhaust. So B1S1 tells you the location of the sensor.
I pulled up a live graph of the bank 2 sensors that have no stored codes. You can see from the coolant temp reading that the engine is still warming up. The B2S2 sensor is the cat monitor and works like a standard O2 sensor. The converter will need to warm up more to stabilize that signal. The B2S1 is the air-fuel ratio sensor for bank 2. The signal from them is very different than a standard O2. I usually look at the S2 sensors on these when trying to determine fuel mixture under load.
Here is a shot of bank 1 under basically the same conditions.
The cat monitor sensor is at 0.00 v and the B1S1 sensor is flat-lined. I don't have any stored B1S2 codes and the B1S1 looks like it might be a subsituted signal for failure management. Interesting. Great learning moment if I had free reign to study this further. But in the real world I need to try and get this car repaired and back to the owner. Best move here is replace the B1S1 with new and take a look again after clearing codes. Also, there was the "tune-up" query.
The spark plugs are NGK iridium and 209,000 miles. No question it does need spark plugs.
Replaced spark plugs, cleaned throttle plate, replaced B1S1 sensor, cleared codes and grabbed bank 1 screenshots. Before fully warm and just as warm. I'm not fully convinced there isn't going to be a code set related to the B1S2 sensor at some point. Right now though no codes and no pending codes. The converter could be recovering from a bad fuel mix and get better. We'll see.
Thanks!
Kenny@ggauto.repair
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