Bank 1 refers to the side of the engine containing cylinder #1. To find it:
1. Locate Bank 1: Consult your vehicle's repair manual or a diagram online (many are available if you search "2002 Dodge Grand Caravan engine diagram"). This will show you which side of the engine is Bank 1.
2. Find the Upstream O2 Sensor: On that side of the engine, you'll find the upstream (front) O2 sensor. It's typically located in the exhaust manifold, close to the engine.
3. Trace the Wiring: The heater circuit is part of the wiring harness that connects to this sensor. The wires run from the sensor back toward the engine control module (ECM). There's no external box or easily visible component for the heater circuit itself; it's integrated into the sensor and its wiring.
Important Note: Diagnosing problems with the O2 sensor heater circuit requires a multimeter and usually a scan tool to check for diagnostic trouble codes (DTCs). If you're having issues, it's best to take it to a qualified mechanic for diagnosis and repair, as incorrectly working on the electrical system can cause further damage.
