What it means
The oxygen sensor signal circuit is shorted to its heater circuit on Bank 2 Sensor 3. This electrical fault can make the sensor reading unreliable.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 3 is a third oxygen sensor where fitted; its location and job depend on the vehicle's exhaust and emissions system. P2236 means this sensor's signal circuit is shorted to its heater circuit, preventing the controller from trusting the Sensor 3 reading for its assigned monitoring function.
Common causes
Most likely first.
- Signal wire shorted to the sensor heater wire
- Melted or damaged sensor wiring
- Damaged or contaminated connector
- Internal oxygen sensor fault
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Check vehicle service information to confirm Bank 2 Sensor 3's location and role, then save freeze-frame data and review its live signal.
- With the exhaust cool, inspect the Sensor 3 connector and harness for melted insulation, chafing, corrosion, contamination, or damage near the exhaust.
- Use the wiring diagram to identify the Bank 2 Sensor 3 signal and heater circuits and test for an unintended connection between them.
- Test the harness and connector separately from the sensor to determine whether the short lies in the wiring or inside the sensor.
- If the wiring and sensor pass, follow the manufacturer's diagnostic procedure to test the controller input.
Common fixes
- Repair melted or chafed Bank 2 Sensor 3 wiring.
- Clean or repair damaged Sensor 3 connector terminals.
- Replace Bank 2 Sensor 3 if testing confirms an internal signal-to-heater short.
- Repair the controller input only if circuit tests confirm a module-side fault.
Can I keep driving?
If the engine runs normally, a short trip is usually possible, but have the fault repaired soon because the affected oxygen-sensor monitoring and emissions checks may not work correctly. Stop if rough running or power loss becomes significant.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.