You got the correct explanation. Since your error code is 1135 vs 135, that indicates your vehicle is a California spec compliant vehicle and uses as the first exhaust gas sensor, what is commonly referred to as an A/F sensor (meaning it is a wideband sensor which gives a more precise measurement of the O2 level in the exhaust), as opposed to the narrowband sensors (which are a bit more like an on/off switch in operation) and are used on non California compliant vehicles and are commonly referred to as an O2 sensor.

The fact that the guy said "bank 1 sensor 1" in the phrase also confirms he was referring to the exhaust sensor. The "bank 1 sensor 1" is the standardized wording that was defined in federal law that mandated OBDII (On Board Diagnostic generation II) back in 1996.

The bank 1 (and 2) refers to the exhaust bank, for example, a V-8 if it used dual catalytic converters (one cat on each cylinder bank), bank 1 would refer to the left exhaust bank and 2 for the right side. Sensor 1 is always the sensor in front of catalytic converter. Sensor 2 is downstream of the last catalytic converter.

No such terminology is used with Mass Air Flow sensors or MAFs.

Before spending the money I would least check the wiring on the sensor to make sure that has been no damage (do you off road or run mud with the vehicle?) The 1135/135 code says the sensor heater has gone open (or wiring open or shorted)

Assuming no visible damage, then go ahead and replace the sensor.

Make sure you give the dealer your VIN number to confirm your vehicle is a California compliant vehicle so you get the correct sensor.

I would guess that the $235.00 quoted is about right now a day for an A/F sensor. They are considerably more expensive than O2 sensors, and its been 5 years since I quoted the $138.00 for an O2 sensor in the above referenced article.