P2243
O2 Sensor Reference Voltage Circuit/Open Bank 1 Sensor 1
Oxygen sensor
Generic OBD-II
Medium
What it means
P2243 means the reference-voltage circuit the ECM supplies to the front (bank 1, sensor 1) wideband oxygen sensor is open. Without that reference the sensor can't report the air-fuel ratio, so the engine falls back to open-loop fuelling. The car still runs, but economy and emissions suffer until the wiring or sensor is repaired.
Medium
Can I keep driving? Drivable, but with the front air-fuel sensor's reference lost the ECM runs open-loop — expect worse fuel economy and possibly rough running until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Poorer fuel economy (ECM runs open-loop)
- Possible rough running or hesitation
- Failed emissions readiness / test
Common causes
Most likely first
- Open in the sensor's reference-voltage circuit wiringLikely
- Faulty front wideband oxygen / air-fuel sensor (bank 1, sensor 1)Common
- Poor or corroded connector at the sensorCommon
- Faulty ECM reference supply (rare)Less often
How to diagnose & fix
Work through it in order
- Inspect the bank 1 sensor 1 connector and wiring for an open in the reference circuit.
- Check the reference voltage at the sensor connector with the key on.
- Confirm the sensor grounds and signal wiring are intact.
- Replace the front air-fuel sensor if the wiring is good but the reference is still open.
- Clear and complete a drive cycle to verify closed-loop operation returns.
FAQ
Quick answers
Is it safe to drive with P2243?+
It runs, but without the front sensor the ECM can't fine-tune fuelling, so economy suffers and it may run slightly rough. Fix it before it affects the catalytic converter.
Can I just clear P2243?+
It comes back while the circuit is open; the wiring or sensor must be repaired to restore closed-loop control.
Related codes
Often seen with P2243
Read & clear P2243 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX