The 2004 Toyota 4Runner Bank 1 Sensor 1 is located on the exhaust manifold before the catalytic converter. It is associated with cylinders 1,3, and 5 (incl' 7 for the 4.7L V8 engine) as they are all a part of Bank 1. Sensor 1 is the upstream O2 sensor that measures the fuel to air ratio coming out of the exhaust manifold. The voltage signals are then sent to the PCM to regulate the mix. If the sensor begins failing You may notice poor gas mileage, failure of the emissions test, rough idling, and a lit Check Engine Light. The estimated replacement cost is around $260 to $300 for parts and $90 to $115 for labor.
Felicitas C.
April 9, 2020
The bank 1 sensor 1 on a 2004 toyota 4runner is located on the side of the exhaust manifold that is further away from the catalytic converter.
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