P2243 signals that the PCM has found an open circuit in the reference voltage supply to the upstream oxygen sensor on bank 1. The code can arise from wiring faults, sensor issues, or, rarely, a PCM problem.
The reference voltage circuit wire or its connector to Bank 1 Sensor 1 may be broken, corroded, or have a poor terminal contact, creating an open circuit.
The sensor's internal reference voltage circuit can fail, presenting an open circuit to the PCM.
A fuse dedicated to the reference voltage circuit may have opened, cutting power to the sensor's reference circuit.
Corrosion or damaged pins can increase circuit resistance, mimicking an open circuit and triggering the code.
The PCM's driver for the reference voltage circuit can fail, but this is uncommon compared to wiring or sensor faults.
No. The PCM is rarely the cause; most often the issue is a wiring fault, connector problem, or a failed sensor.
Yes. If the sensor's internal reference voltage circuit fails, it will appear as an open circuit to the PCM.
Fuses for the reference voltage circuit can blow, but this is less frequent than wiring or sensor failures.
Clearing the code after repairing the circuit is recommended, but the code will return if the fault persists.