What does it mean?
P1110 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: O2 Sensor Circuit (Bank 2-Sensor 2) Short to B+ .
Symptoms
- Check engine light on and the catalyst monitor for Bank 2 unable to run
- Readiness monitors incomplete, which prevents the vehicle passing an emissions test
- Downstream sensor voltage in live data pinned near battery level instead of switching
- Slight increase in fuel consumption where the rear sensor trims the mixture
- Little change in drivability, so the fault is often discovered only when scanning
- Fuse for the shared heater supply blowing occasionally
Likely causes
- Sensor loom chafed against a live wire or an underbody clip on the Bank 2 side
- Insulation melted where the harness contacts the exhaust or a displaced heat shield
- Corrosion or standing water inside the connector bridging the signal pin to the heater feed
- Internal short in the sensor joining the heater supply to the signal element
- Mis-pinned or incorrect sensor fitted during an earlier repair
- Failed module input stage, considered only after the harness and sensor test good
How to fix it
- Check the Bank 2 downstream sensor voltage in live data; a reading far above the normal switching band confirms the fault
- Unplug the sensor, switch the ignition on and measure the signal wire to ground — battery voltage with the sensor removed proves a harness short
- If the wiring is clean, measure between the sensor heater and signal terminals for an internal short
- Inspect the loom along the exhaust and floor pan for melted or rubbed insulation and repair it properly
- Dry, clean and reseal any connector showing water or corrosion
- Confirm the correct sensor part and pin arrangement, especially after previous exhaust work
- Repair the harness or replace the sensor, then verify normal switching and clear the code