Code P2237 indicates that the engine computer has detected an open circuit in the positive current control side of the oxygen sensor heater for Bank 1 Sensor 1. This means the heater element inside the O2 sensor is not receiving the electrical current needed to warm up, preventing the sensor from entering closed-loop operation quickly. It typically points to a physical break in the circuit rather than a short to ground or power.
The internal heater resistor inside the Bank 1 Sensor 1 oxygen sensor has burned out or broken, creating an open circuit internally.
The wiring harness leading to the sensor has a broken wire, severe corrosion, or a disconnected pin in the electrical connector.
A blown fuse in the power distribution center that supplies battery voltage to the O2 sensor heater circuit.
A failed driver circuit inside the Powertrain Control Module that is unable to supply or control the positive current, which is very rare.
You can drive short distances, but the engine will run in open loop until the sensor warms up naturally, which decreases fuel economy and increases emissions. Prolonged driving may damage the catalytic converter.
It is the most likely cause, as the heater element inside the sensor frequently burns out. However, you must test the wiring, fuses, and connector before replacing the sensor to avoid unnecessary repairs.
Rarely. Drivers and technicians are frequently told to replace the PCM for this code, but that is usually incorrect. The problem is almost always a failed O2 sensor, a blown fuse, or damaged wiring, not the computer itself.
Bank 1 refers to the side of the engine that contains cylinder number one, and Sensor 1 refers to the upstream oxygen sensor located before the catalytic converter.