P2243O2 Sensor Reference Voltage Circuit/Open (Bank 1 Sensor 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2243 flags an open reference voltage line on the front wide-band sensor of bank 1, i.e. the Nernst-cell lead (RE/UN on Bosch sensors, VS on NTK). Ford's OBD summaries set it on Bosch parts when the sensor voltage sits above 4.7 V or below 0.2 V for 10 s; on NTK parts the interface chip reports the break itself. GM's 2005 V6 tables and the 2010 Saab 9-5 2.0 turbo use the same voltage window with cell resistance above 570 ohms, as a two-trip Type B code. On the 2004-05 Saturn Vue 3.5 V6 the pump-cell voltage must swing both above 4.8 V and below 3.4 V fifty times. Honda bulletin 14-002 ties it on 2010-11 V6 models to a broken sensor tip, often with P0420/P0430; Ford reflashes the 2020 Explorer 2.3 (20-2217). P2247 is bank 2, P2245/P2246 low/high.
- What you may notice
- Check engine light
- Higher fuel consumption from open-loop fuelling on bank 1
- Catalyst efficiency code P0420 alongside it if a sensor fragment damaged the converter
- Likely causes
- LikelyBroken reference voltage (Nernst cell) wire or pushed-back pin between sensor and ECM
- PossibleSensing element cracked or tip broken off, for example by thermal shock
- RareCorroded or loose sensor connector
- RareEngine software that sets the code falsely (update available for some models)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.