The P2236 code indicates that the engine control module has detected an electrical short between the signal circuit and the heater circuit of the oxygen (O2) sensor located at Bank 2, Sensor 3. This prevents the sensor from accurately reporting oxygen levels in the exhaust stream.
The internal insulation of the O2 sensor has degraded, causing the signal and heater elements to short together.
External wires have chafed, melted, or frayed, allowing the signal wire and heater wire to make direct contact.
Moisture or contaminants have entered the sensor connector, creating an electrical bridge between the signal and heater pins.
An internal failure within the engine control module has caused a cross-circuit between the two functions.
Because Sensor 3 is typically a downstream monitor used for catalyst efficiency, it rarely affects engine performance or driveability, though it will trigger a malfunction light.
No. It is highly uncommon for the PCM to cause this code; the issue is almost always located within the sensor itself or the wiring harness.
In most cases, yes, as internal sensor shorts are the most common cause. However, you should verify that the wiring is not melted first to avoid damaging the new sensor.